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THE MAKING OF 
A MECHANICAL 
OPTICIAN 


A PRACTICAL TREATISE ON THE 
MECHANICAL WORK OF OPTOM¬ 
ETRISTS AND OPTICIANS 



THE KEYSTONE PUBLISHING COMPANY 
809-811-813 NORTH 19TH STREET 
PHILADELPHIA, PA. 


COPYRIGHTED 


This Space 
Held 

For Advertisers 



THE MAKING OF A MECHANICAL OPTICIAN 


CHAPTER I 


Selecting, Installing and Operating the Machinery 

In beginning this treatise we have in mind partially the 
optician who is considering the advisability of installing a plant 
to do his own work, and, naturally, the first question to decide is 
whether it is advisable to install such a plant. The arguments in 
favor of doing so are the following: The accommodation to your 
customer, the new customers it will bring by advertising that you 
do your own work and the extra profit. The arguments against it 
are: The extra responsibility and labor it will put upon you; have 
you enough prescription work to make it an object, and if so, can 
you afford to hire a man, and would it not be advisable to use the 
time that you would put into this work to develop your refracting 
business ? 

' This matter you can best decide for yourself, but, assuming 
that you decide to take the step, the next thing is to lay the plans 
for your shop and select the machinery. 

It was formerly the custom to engage an attic room in some 
old building on a side street, order a grindstone and engage car¬ 
penters and machinists to fit it up. As it was impossible to esti¬ 
mate the expense, it frequently was exorbitant. Now that has all 
changed, as it is possible to purchase an entire outfit, ready to run, 
at a nominal cost. This not only saves a great deal of worry, but 
you can figure the cost almost to a cent. 

Another great advantage is that the outfit, sold by the whole¬ 
salers to-day, can be used in any office, even with a rug on the 
floor, and can be kept as clean as a piece of furniture. 

The best place for a bench depends somewhat on the circum¬ 
stances. Some prefer to have an extra room for this work; others 
fit up part of the refracting room or the reception room. If you 
have an office, consisting of only one room, you can perhaps select 
a corner near a window, and, if you prefer, you can stand a screen 
in front of it. If you have a store, it will be a good idea to place 
the bench in a prominent position, even in the window, if possible, 


1 




2 The Making of a Mechanical Optician 

thus enabling you to take advantage of the advertising possibili¬ 
ties. This question of space and location, however, is not of very 
much importance, as there are benches on the market that require 
very little room. We have in mind particularly the Simplex 
Bench, which is but 4 ft. long by 16 in. wide. 

Having well considered these facts, we now proceed to select 
the outfit. This is a matter which should be given considerable 
attention. It certainly is false economy to buy cheap machinery, 
as it not only gives trouble, but wears out sooner and has to be 
replaced in a few years. With the best, a great deal of work is 
done automatically, requiring less time and attention, and one does 
not need to be an expert to do good work. If you are not limited 
as to space, we would suggest a bench 4 ft. long by 32 in. wide. 
This will give you sufficient room to lay out your work, so that you 
can handle it easily. 

After deciding on the bench, the next thing is to select the 
frameless machine. The four most prominent on the market are 
the Acme, Gem, Monarch and Simplex. The Acme is a large 
machine, with a stone 24 in. in diameter and in. face. It is 
designed to do heavy work and can be used for both prescription 
and stock grinding. By this we mean grinding up quantities of 
interchangeable sphericals and cylinders. The Gem is a medium¬ 
sized machine, designed more especially for prescription work, 
but stock can be ground on it also, but not in such large quantities. 
It has a composition stone, 18 in. diameter by 2 in. face, and it has 
been very popular with the shop men for several reasons. In the 
first place, it is very simple and can be taken apart and put 
together very easily. It also has a hand wheel for turning the 
lenses, which is very convenient when in a hurry, to grind off any 
bunches on the lens, if not properly cut. The Acme and Simplex 
have a hand wheel for the same purpose. 

The “Monarch” is a machine of medium size, not as large as 
the Gem or as small as the Simplex. It has a 16-inch composition 
stone with either lyi or i^-inch face and requires only a quarter 
or a sixth h. p. to operate. This machine will edge from one 
single lens to as many as will occupy the width of the stone, all 
lenses being constantly kept on the stone. The stone can be tipped 
back out of the trough when desired. The machine can be used 
on the bench or separately with stand or legs. 

Whichever, machine you decide on be sure to get a composi- 


3 


The Making of a Mechanical Optician 

tion stone, as a Craigleith requires constant care and never works 
as satisfactorily. These composition stones are very hard, and will 
keep in shape sometimes for years. Either size is all right for 
hand work. We might state that it is really better to have a 
separate stone for hand work, as it enables you to keep your 
frameless machine in better condition. In grinding over a 



Figr. 1—Reception room and modern workbench 


machine the water runs off the hands on to the machine. This is 
full of grit, and unless you clean the machine every day it will 
soon become gummed up and in time refuse to work. If you 
install the Simplex, however, you should have an extra stone, 
which can be obtained for about fifteen dollars. The Simplex is 
the latest machine on the market, and is designed particularly for 
prescription work. The stone is but lo in. diameter and i in. face. 
















4 


The Making of a Mechanical Optician 

The machine, however, is built just as heavy as the large ones, and 
particular attention has been given to the wearing qualities. The 
idea of using this small stone is to take up less space and to 
require less power (a i/6 h. p. motor will operate it), and then the 
stone can be replaced at a small cost. Another advantage is in 
case of repairs it can be boxed easily and shipped to the factory at 
a small expense. This will be appreciated by anyone having had 
occasion to renew broken parts or turn up a stone on a large 
machine. Frequently it has been necessary to pay a man’s ex¬ 
penses from the factory or jobbing house to do this work, or if the 
machine has to be sent to the factory it must be crated and shipped 
by freight. 

The selection of one of these machines will depend on the 
circumstances and requirements of your work. It should, how¬ 
ever, be placed at the right hand end of your bench, as you will 
find it more convenient. There are many good drills on the 
market, and samples of these can be seen at all the large jobbers, 
or a good idea of them can be obtained by consulting the different 
catalogues. You can obtain a low-priced diamond drill, without a 
centering device, that does excellent work, but requires more 
experience in centering the lenses. There is a separate centering 
device on the market that can be obtained for a small sum. 
Opticians having old-style drills will find this a great convenience 
in marking lenses for drilling, as it centers them instantly and 
accurately. It also has a scale for drilling above and below center. 

If you can afford it, we should recommend a drill with the 
centering device and also an arrangement for drilling torics, such 
as the Universal (Standard Optical Company’s) or the American 
Optical Company’s drill. You should, by all means, use a diamond 
point, although these are not guaranteed. With a little instruction 
and by using care you will seldom break one. In selecting the 
diamond we would recommend a white splint, as this has a rough 
point and cuts faster. It also can be sharpened at less expense. 
If you break it, you can replace it for about five dollars. The 
turned diamond can be had in white stones or black carbon, and 
these cost from twelve to eighteen dollars. These are, perhaps, 
less liable to break, but do not cut as fast. (In reality, they grind 
a hole.) They cost more to sharpen, besides having to be done 
oftener. 


The Making of a Mechanical Optician 


5 


Next is the cutter, and this should be placed on a square 
board, so that it can be moved back out of the way when not in use. 
There are only four on the market, which are used to any great 
extent, and these are: The American Optical Company; Little Gem 
(Bausch & Lomb Optical Company) ; Standard and Globe. The 
American Optical Company’s is arranged so that most of the dif¬ 
ferent shapes and sizes can be cut by adjusting the micrometer 
head according to a scale furnished with the machine. The Stand¬ 
ard is operated by one large pattern with a groove in the under 
side. In place of a micrometer there is a five-sided barrel with 
the two rolls that run in the groove in the pattern arranged at 



Fig 2—The old-time shop 


different distances, so that by turning it you can cut the shapes, 
having a difference between the length and width of ten, nine, 
eight, seven and six millimeters. This machine is furnished with 
a steel wheel, but it can be obtained with a diamond, by pay¬ 
ing extra. 

The little Gem has an adjustable pattern, and by adjusting 
both the pattern and micrometer head, according to a chart fur¬ 
nished with it, you can cut most all the ovals. While this scale 
is nearly right, we would suggest that you make a scale of your 
own, for the regular shapes, for accurate work. This can be done 
by cutting old lenses and measuring them until you find just the 
right amount to allow for grinding. The Globe is arranged by a 
series of patterns, so that it will cut any size or shape. These are 
changed instantly by lifting the top gear. It has a micrometer. 







6 The Making of a Mechanical Optician 

arranged with a pointer, so that the frameless sizes are read in 
millimeters, and the frame sizes in the regular way, i, o, oo, etc. 
This scale is also arranged so that it is set for regular and full eye, 
without any difficulty, and without consulting a chart. To cut a 
lens 40 X 33, subtract the width from, the length (this is seven 
millimeters). By placing No. 7 pattern in the machine and setting 
the pointer at 40 mm., you get the required size. These patterns 
also interchange with those on Acme and Simplex machines. 
This you will find very convenient. 

Just here we will put in a word about diamonds. Quite fre¬ 
quently we hear that someone wants a cutting diamond sharpened. 
This is impossible, as a cutting stone is a natural formation, and 
although it can be reset many times, it cannot be sharpened. In 
resetting, the stone is taken out of the mounting, and reset at a 
different angle. These stones have from one to four cutting 
points, and after it has been reset two or three times, using the 
same point, it is then necessary to find a new point. Drills are 
made of splints, which are obtained by cleaving large stones, or 
from natural stones, sharpened or lapped, by hand. These can be 
resharpened a number of times, and should be kept sharp to do 
quick work. The bench should be equipped with a buff-head, 
having a taper screw and chuck, for small drills, burrs, polishing 
wheels, etc. As these are not furnished with the outfit, and they 
must be selected separately, we would recommend the following: 
About six small twist drills, of different sizes, including the size 
for frameless glass screws and stud screws; two sizes of solder 
burrs, for burring out eye wire after soldering; two sizes of 
temple burrs for burring the joints of temples; a brush wheel; a 
felt wheel, about three or four inches diameter, will do; a cotton 
wheel, about six inches diameter. This outfit will do all the work 
you are required to do. 

Next is the motor, and the first thing to do is to inquire of 
the power company what the current is. It probably will be either 
direct, no volts, or alternating, no volts, 60 cycles, and in asking 
for quotation, or ordering an outfit from the jobber, be sure and 
give this information, as it makes about twelve or fifteen dollars’ 
difference in price. All quotations are given with direct current, 
and the alternating costs extra. If you have a direct current, a 
h. p. shunt-wound motor should be used. This maintains its 
speed without the load, while a series-wound will speed up and the 


The Making of a Mechanical Optician y 

load must be kept on to hold it down. You should see that you 
get a quiet one, as a magnetic hum is very disagreeable. There is 
a rheostat, or starting box, furnished with it, and if the outfit is 
bought complete it will be wired up on the bench with a switch- 
and cut-out. It is only necessary then for the electrician to con¬ 
nect the wires, and you are ready to start. 

If you have alternating current, we should recommend an 
automatic starting, h. p. This requires no starting box, which 



Fig. 3— A. modern optician’s workbench 


is quite large for this current, and is also started quicker. In 
buying a motor, the speed is an important matter, and many of the 
shops that have been fitted up by opticians themselves are equipped 
with high-speed motors. These have been installed, either from 
inexperience, or on account of the low price. A slow speed motor 
runs with less noise and there is less slipping of the belts. Then 
again you do not require such large pulleys. They are, of course, 
higher in price, but are worth the difference. In belting up the 
motor, an endless belt should be used, so there will be no pounding 











8 


The Making of a Mechanical Optician 


of the lacing and no vibration. This is very important, if you 
want a smooth running outfit. 

We have now given you a general idea of the outfit, and we 
think you will see that it is a great deal better to purchase this 
complete and obtain the benefit of the experience of the optical 
machinery manufacturers. They have made a study of shop 
troubles, and have succeeded in eliminating many of them. Occa¬ 
sionally you find an optician who has built his own bench, with 
the idea of saving money, but in the end he finds it has cost more 
than any first-class outfit on the market. 

Now in regard to tools. These, of course, are not furnished. 
You will need the following: A pair of breaking tongs, cribbers, 
a hand-diamond, a set of the brass patterns for cutting odd 
lenses, round-nose pliers, snipe-nose pliers, optician’s hollow chop 
pliers; flat-nose pliers, strap pliers, angling pliers, cutting pliers 
(and as there are plenty of special pliers on the market we would 
suggest looking them over and getting a few of the best ones) ; 
an assortment of files, including rat-tail; a millimeter rule; 
broaches, drilling fluid, bifocal cement and polishing material. 

This covers most of the necessary tools, and can be added to 
as occasion requires. When the outfit comes to you, it will be 
crated, and after it is opened up, set in place and connected with 
the current, it should be wiped up to take off the grease which is 
put on to keep it from rusting in transit. Then look at the bear¬ 
ings, especially the boxes on the stone and main shaft. These 
may have been set up tight in shipping. If so, the screws should 
be loosened a little until they turn freely. 

Everything should then be well oiled and then the motor can 
be started. It should be run a few hours, feeling the bearings 
occasionally to see that they do not warm up. If so, they should 
be loosened up a little more. Possibly the belts may be a little 
loose, and even if they are all right at first they will have to be 
shortened later, as all new belts will stretch. If the motor is a 
good one it will have an adjustable base, so that it can be adjusted 
to take up the slack. After taking up all you can in this way, have 
a piece taken out at some belt manufacturer’s, and do not attempt 
to lace it. All other flat belts will be laced, however, and these 
you can take up yourself, but always use light, thin lacings to 
make it run as smoothly as possible. The round belts will prob¬ 
ably be put together with hooks, and they will require shortening 


The Making of a Mechanical Optician 9 

very often. In shortening belts do not get them too tight; it is 
better to run them a little loose, and if they slip it is probably be¬ 
cause they are too hard and dry. By applying a little castor oil, 
occasionally, on the inside, while it is running, it will make them 
soft and pliable. Never use resin or anything of that nature. 

After everything is running smoothly, you can then put water 
on the stone and place some thick lenses in the machine and allow 
them to grind a while. In starting a new composition stone, it 



Fig. 4—Outfit for prescription work 


will absorb the water very quickly, and for the first hour or so 
watch it carefully and see that it does not run dry, as this will 
rough it up and may require turning. The stone can be kept wet 
by a drip, either from a tank, or it can be connected with the water 
supply, but you should then arrange for the outlet, or it is liable 
to overflow. A very popular way is to have a sponge pan on the 
back, filled with water, and the sponge will act as a wick, keeping 
just enough water on the stone. Some of the machines are sup¬ 
plied with this sponge pan and we recommend this method, as it is 
much cleaner. Some of the stones, shipped from the factory, are 







10 The Making of a Mechanical Optician 

not quite ready to grind on, but by running thick lenses in the 
machine for a while it will smooth up very quickly. If it does not, 
a piece of the same material, held by the hand, will polish it. 

All the frameless machines are equipped with truing devices, 
and it is well to true the stone up every little while to keep it in 
perfect condition, rather than allow it to get badly out, as it is then 
quite a job to get it back. All that is necessary to do is to set the 
truing device up until the carborundum stone just touches the 
grindstone and allow it to run a few minutes until you cannot 
hear it grind. As the stone oscillates it trues itself automatically. 
If your stone, for any reason, should get badly out of true, you 
should turn it with a carbon or black diamond, or you can use the 
new tool on the market similar to a carbon. This is placed in the 
truing device and operated the same as the carborundum block. 
After you have turned it true, it will be very rough; then by 
replacing the carborundum you can smooth it, the same as before 
described. 

We will describe the use of the drill and cutter later, but they 
can be tried, and if they do not suit have them exchanged at once, 
as they are not guaranteed. Do not spoil them and then claim 
they were never right. If you do not get good results in cutting, 
it is probably because you have not used just the right pressure. 
Start lightly, ahd on each lens gradually increase the pressure 
until you get a good clean cut. 

The cost of operating is trifling, as a %. h. p. motor uses very 
little current, costing not over one dollar a month. 

The accompanying illustrations will give an idea of the 
arrangement of the benches most in use. 


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For Advertisers 


CHAPTER II 


Lenses—Marking and Cutting 

In selecting the stock of lenses quite a little capital can be 
invested, or you can start small and increase it from day to day. 
A stock varies in price from $50 to $500, but the usual amount 
invested is from $100 to $200. This will include principally + C 
-b compounds, a few — C —j piano cylinders, oval or round 
Dcx. and Dec. sphericals, Pcx. sphericals, regular and piano 
wafers. If you use large, full eye lenses it will be better to have 
the sphericals in round, as these will grind 40 mm. or 41 mm. in 
length and any width. The +3 — — 3 + compounds, 

compound wafers and rough cylinders (provided you are to do 
surface grinding), can be ordered daily, until you can afford to 
stock them. 

Compounds are put up in single envelopes, with the axes 
dotted, cylinders in packages of half dozen pairs, the axes dotted, 
and sphericals in the same way, but not dotted. By this you will 
see that it is better to buy cylinders and sphericals in original 
packages, although compounds can be ordered three pairs of a 
number. If you have had no previous experience in ordering, a 
good plan is to see your jobbers and tell them that you wish to 
place an order for a quantity of rough lenses, stating the amount 
you wish to invest, and let them submit lens sheets, showing the 
assortment and quantities that can be obtained for this figure. 
As they are constantly making them up, they can best advise you. 
You can then look it over and change it as you see fit. If you 
have made no provision for carrying your stock, we would sug¬ 
gest getting an uncut lens cabinet. This is made of oak, with 
galvanized iron drawers, with wood front and back. The small 
drawers are partitioned off for compounds and the large for cyl¬ 
inders and sphericals. The latter have pressed paper partitions in 
front for single lenses, without wrappers, and the surplus is placed 
in the rear. This can be obtained much cheaper than you can 
have one made and will last a great many years. 

A good way to keep your stock ordered up is to have a box 


13 



14 


The Making of a Mechanical Optician 


handy, and as you use the compounds put the envelopes into it and 
order from them. 

In selecting the lenses for a prescription it will be necessary 
to have a pair of calipers or lens gage, graduated in 1/5 mm. 
With this the lenses are calipered in the center, allowing 2/5 mm. 
for each diopter. For example, a piano lens is the same thickness 
on the edge as in the center, and if you wish to make a pair of 
glasses two-strap thickness, having a piano in one eye and -f- i in 
the other, we select the piano first 2 mm. thickness and the -|- i, 
2 2/5 in the center. If the lens was concave, it would be i 3/5 mm. 
In this way the edges are made the same thickness. In cases 
where there is to be a compound in one eye and spherical in the 
other, it is well to look at the compound and use your judgment 



as to which would be best—a double convex or periscopic. If the 
compound is -f C +, a Dcx. would make a better match; 
whereas if it were -f C —, a Pcx. would be nearer the curve. 

For marking you will need quite a stiff pen that does not 
scratch, a bottle of black waterproof ink and a protractor gradu¬ 
ated in five degrees. These are furnished by some jobbers, as 
advertisements, with a decentering scale on the back, which is 
very convenient. For cross lines use a card about the size of a 
reading test type, and draw heavy black lines at 90° and 180°. 
This will be used for medium and strong powers; for the 
weak powers draw the lines on a wall about twenty feet dis¬ 
tant. In marking, first decide which surface will be next the eye 
and then always mark on this surface. The rule is, the greatest 




The Making of a Mechanical Optician 


15 




concavity or the least convexity, next to the eye, always having 
the cylinders on the same side, except in extreme cases. We will 
first select a sphere, and all that is necessary in this case is to dot 


the center. We find the center by looking through the lens at 
crossed lines, and the lines will appear broken (Fig. 5). 

Then move the lens until the lines are continuous and place a 


Figr. 7 


dot where the lines cross (Fig. 6). A cylinder usually has the 
axis running from corner to corner, and in lining it up the lines 
will appear broken and perhaps twisted (Fig. 7). By turning the 
lens they will line up so that they appear straight and by moving 


Fig. 6 




i6 The Making of a Mechanical Ophcian 

in a horizontal and vertical position they will be continuous. Then 
place two dots on the lens, one at the top and one at the bottom. 
Now lay it on the protractor with these dots at whatever axis the 
lens is to be cut. Draw a line across the lens at axis iSo°. This 



Fig. 8 


will be the mechanical axis or cutting line, as it is usually called. 
Remember that whatever axis is to be cut the cutting line is 
always drawn at i8o°. For example, axis 45° will be placed, as 
shown in Fig. 8, axis 90° as Fig. 9. 



Fig. 9 


A compound is lined up in the same way as a cylinder, and 
the lines will look the same, but when you have it in position three 
dots must be placed on the lens, one at the top, one at the bottom 
and one in the center. It is then laid on the protractor the same 













The Making of a Mechanical Optician 17 

way, but be sure that the center dot is on the center of the chart 
or your lens will be decentered. If you wish to obtain some pris¬ 
matic power you can decenter it, using the following rule: A lens 
decentered ten millimeters will produce a prism power of as many 
diopters as the focus. Thus a + i D. lens, decentered 10 mm., 
will have a prism power of i D. By this you will see that a + 



Figr. 10 


I D. lens, decentered, 2.5 mm., would give us D. prism. A 
mistake is often made, however, in ordering a lens decentered 6 
or 8 mm. This cannot be done, as the stock lenses are not large 
enough. Extra large lenses could be used, but these would cost 
more than to have a pair surface ground. With the large sizes 


“hi>,00^ STO 




Figr. 11 


that are now being used a lens cannot be decentered over 2 mm. 
In marking a lens to be decentered, it is dotted in the usual way 
and then moved on the chart the amount necessary and a cross 
line drawn on the cutting line (Fig. 10). Before the lenses are 
cut they should be neutralized to be sure the power is correct. If 
you depend on the lens measure it should be kept accurate by 
frequent adjusting, and if you do not have two, one for American 











i8 


The Making of a Mechanical Optician 


Optical Company and one for Bausch & Lomb, you should make 
an allowance of .03 D. for every diopter. We prefer to use a lens 
measure, graduated for Bausch & Lomb stock, and then add the 
required amount when measuring American Optical Company s 
stock. 

We will not describe the marking of prisms, as we should 
recommend that they be sent to the prescription houses. Very 
little can be saved in buying them uncut, and the responsibility of 
breaking is too great. This also applies to torics, but if you 
prefer to grind these yourself they are handled just the same as 
flat lenses in marking. We will give a few suggestions for order¬ 
ing, so that you will be sure to get the best results. If all pre¬ 
scriptions for torics were filled as written a great many would 
have no toric effect. 


i-WOSjoX 



Fig. 12 


You should, of course, understand the transposition of lenses, 
and transpose them to the best form before sending in the pre¬ 
scription. If you do not you should state that you want the pre¬ 
scription filled in the best form. In ordering plain cylinders it will 
make no difference which way they are ordered, unless wafers are 
to be fitted. If a -f cylinder was ordered, the lens would be 
ground as written and would have the cylinder on the outside, and 
a 6 D. curve on the inside (Fig. 11). If a — cylinder was ordered 
it would be ground with the cylinder on the inside and a -f- 6 D. 
curve on the outside (Fig. 12). If wafers were to be fitted, the 
cylinder should be on the outside, so that the wafers could be 
cemented to the inside surface. It would then be necessary to 
transpose to a compound. For example: A — .50 cylinder, axis 
180°, would be .50 sphere C + -50 cylinder, axis 90°. This lens 
would, of course, cost extra. 

The ordering of compounds is a more difficult matter and the 
optician should know just what surfaces are to be ground. For 
example: If a -|- i sphere C -f .50 cylinder, axis 90°, was 
ordered, it would be ground as written, and the lens would be 





The Making of a Mechanical Optician 19 

+ 63 + 6.50 on the outside and a — 5 sphere on the inside 

(Fig. 13). 

By this you will see that the toric effect has been reduced i D. 
While it does not matter much in this case, the toric effect is 

+6.00- f 6 S 0 

Fig. 13 

gradually reduced until with a combination of + 6 sphere 3 + 
.50 cylinder, axis 90°, it has a piano effect and this would be 
ground with + 63 + 6.50 on the outside and piano on the 
inside (Fig. 14). 

All and + combinations with a spherical stronger than + 
I should he transposed. For example: + 3 sphere 3 + i cyl- 

+606^f6SC> 





Fig. 14 


inder, axis 90°-, if ground as written, would have only — 3 D* 
inside curve. If it is transposed it would be ground with + 10 
D. outside and — 6 3 — 7 inside (Fig. 15). This lens costs 
more, but will give better satisfaction to your customer. If you 



■ f /d.00 

9. c uri/e^ 



-/l,.C0=-JC0 

Fig. 16 


understand this before ordering you can explain it to your cus¬ 
tomer and charge more for your lens accordingly. Concave com- 











20 


The Making of a Mechanical Optician 


binations are transposed in the same way. When wafers are to 
be fitted they should be transposed so that the cylinders are on 
the outside. 

In combinations where the spherical power exceeds + 
distance lenses should be ordered on n + p curve. Thus a combi¬ 
nation 3 sphere 3 “h t cylinder would be -|- 9 3 10 on the 
outside and — 6 sphere on the inside (Fig. 16). This gives you 


i-3,oo--t/.ooA,xJO ‘‘ 

Fig:. 16 



the regular — 6 toric effect, and although it increases the expense 
it makes a much better lens. 

In selecting stock for bifocals the upper lenses are marked 
as usual with one exception, and that is, the wafers are always 
placed on the inside when possible. For sphericals, periscopic 
lenses are used for the uppers and “regular” wafers are cemented 
on the inside. For example: Prescription distance -f- 2; reading 
+ 4, select + 2 Pcx. and a “regular” wafer, having a -|- 2 power, 
which is the necessary addition for reading. This will be -]- 1.25 



on one side and -f- .75 on the other. The + 1.25 side is 
cemented to the — 1.25 curve on the upper lens. The -f- .75 on 
the outside of the wafer and the -]- 3.25 on the outside of the 
upper lens will then give us the required focus (Fig. 17). The 
contact surfaces are not considered in any way, other than that 
they must fit perfectly as they have nothing whatever to do with 
the focus of the lens when the index of the glass is the same. If 







The Making of a Mechanical Optician 


21 


it is different, as in fused bifocals, it is then an important matter, 
and must be taken into consideration. 

For cylinders piano wafers are used and cemented on the 
piano side. You will have no trouble with these, as the power of 
the wafer is all on one side. Be careful, however, never to cement 
a wafer on a cylinder surface, as the cylinder effect is then de¬ 
stroyed. Compounds are a little more difficult, but are simple 
when understood. The wafer is usually placed on the inside in 
weak combinations. The only reason for this is to make them 
more invisible. Whichever way they are made the wafer will have 
to be cemented to the spherical surface, and here is where you 
will, perhaps, be confused in marking. Be sure that you lay the 



lens on the protractor, with the surface upward, that is, to be next 
the eye. If the spherical is to be in, mark it on the spherical side. 
If the cylinder is in, mark on the cylinder side. You can readily 
see that if the axis is to be 45, with the cylinder surface out, and 
you mark it on the cylinder side, and then turn it over, the axis 
will be 135°. In selecting the wafers the contact surface will be 
the same power as the spherical surface on the compound, but the 
curve will be the reverse. To this power add the amount to be 
added for reading and you will have the outside surface. For 
example: Prescription + i C + - 50 , axis 90°, distance add + 2 
for reading. We will first select — i to fit the -f i surface, and 
by adding the -f 2 for reading we have -f- 3. Then the wafer 
wanted is — i 3 + 3- 






22 


The Making of a Mechanical Optician 


You should first become familiar with the working of your 
machine. Read the directions and be sure that you understand 
how to set it for size. Some of them are set by charts. That is, 
for length and width. Others are set by the difference between 
the length and width. In other words, the patterns are marked 
from 4 to 12, so that 40 x 33 would require No. 7 pattern, and the 
gage is set at the length, 40 mm. In cutting for frameless, allow 
I mm. on the length and width. For above size it should be cut 
41 X 34. For frame size, it is best to cut a lens and try it in the 
frame, allowing about to 3/16 inches between the end piece. 



according to the thickness. After you have ground one or two, 
you can judge for yourself just the amount you will need for 
grinding. 

When the machine is in position to cut the handle on the top 
gear should be at the right. It should always be turned to the left, 
making one revolution, and stopping at just the point where it 
started to cut. Never, under any circumstances, run by this point, 
as you will spoil the diamond. If, for any reason, you do not get 
a satisfactory cut it is better to turn it over and try again on the 
other side. In placing the lens on the pad see that it fits perfectly 
flat and does not rock. If you have a universal pad it will 
be all right; but if your machine has a number of pads select 
the one nearest the curve of the lens. Also cut on the surface 
having the least power on the nearest to piano. In laying the 
lens on the pad, the cutting line should be on the 180° line on 




The Making of a Mechanical Optician 23 

the cutter, with the center on or under the centering pin, which¬ 
ever way the machine is constructed. When the lens is in position, 
raise it to the diamond by pressing the hand lever on the left side. 
Start gently at first, increasing the pressure gradually, turning the 
lens slowly at the same time. Some diamonds require more pres¬ 
sure than others, but you must experiment carefully until you 
find that you get a perfect cut (Fig. 18). This you will see has 
a sharp line which runs almost through the lens. If you put too 
much pressure on it you will have a scratch (Fig. 19). This lens 
you will find very difficult to break down, and probably break over 
the mark, unless you are extremely careful. 

There is another way to cut a lens without marking and in 
this way you turn the pad in the machine so that the line corre¬ 
sponds to whatever axis you are to cut on the graduated scale. 
The lens is then placed with the axis dots on the line on the pad. 
This will give you the same result, and, although it saves time, it is 
not so accurate. Strong lenses and high curve torics can be cut 
better by hand. These are marked in the same way, selecting a 
brass pattern the exact size of the frame or the dimensions of 
the frameless lens to be ground. Lay this on the lens with the 
three holes over the dots, or on the cutting line, holding it in the 
left hand with your thumb on the pattern. Use the diamond in the 
right hand in a vertical position, the same as a pencil, or with the 
handle between the index and third fingers. Cut lightly around 
the pattern and be careful not to run over the line. 

In breaking down, start at the end of the lens and crumble off 
the glass until you reach the cut. If it is cut well you can then 
grip the glass on the side and you will find that it will break off 
easily. If you do not get a good cut break off a little at a time 
with the breaking tongs, and after you have gone all the way 
round you will, perhaps, have left a number of points. Then take 
the cribbers, using them as a pair of scissors, and trim it up. 
This tool is one of the most difficult to master, but by persevering 
you will soon learn. 


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CHAPTER III 


Lens Grinding 

For hand grinding a large stone is preferable, and the size 
most commonly used is 24 inches diameter by ip2 inches face. 
Craigleith, corundum or carborundum can be used, but the corun¬ 
dum, called by the trade name Alundum, is the best. This size 
should run at about 225 revolutions, or 1415 feet per minute. To 
obtain the proper speed for any size stone, multiply the diameter 
by 3 i/7> and then multiply by the number of revolutions 
desired. 

The stone should turn away from the grinder and should be 
kept wet by a drip or sponge on the back. It is unnecessary to 
have a great amount of water on the stone, so that it will fly all 
over everything, but keep it just wet enough so that it will not run 
dry. With ordinary care the stone will keep in shape, but if it 
becomes rough it should be smoothed with a piece of the same 
material. Do not use a piece of craigleith on an alundum, or 
vice versa. 

The turning can be done by hand, but not as well. When 
turning without a truing device the diamond is held in the right 
hand and the left is used to steady and guide it. A board is 
placed on the trough at the back, so that it just clears the stone; 
this is used as a rest. The diamond tool is then started at either 
edge and rolled along, so to speak, on the rest, so that the stone is 
cut evenly. Enough should be taken off so that the surface is 
square and true. A carborundum block should then be used on 
the back to smooth it, or, in other words, take out the ridges left 
by the diamond. The stone should then be honed with a piece of 
the same material, held in the hands, on the front. 

When the lenses are cut and ready to be ground, they should 
be rinsed in water to remove all the glass dust, otherwise this gets 
into the fingers, and as the lens is revolved, it scratches the sur¬ 
face. In large shops there is apt to be quite a little waste from 
scratching, and this is usually the cause. A rubber coin pad, such 
as are often seen on counters, and which can be obtained in any 


25 


26 The Making of a Mechanical Optician 

rubber store, is convenient to lay lenses on, and prevents 
scratching. 

If the lenses are well shaped with the cribbers, there is very 
little difficulty in putting on the level, but if there are bunches and 
points to be ground off, this is where skill is required. The 
shaping is the first important point, and the eye should be trained 
to judge ovals. The axis should also be watched at the same time 



and see that you do not grind it off. If the lens is cut large, and 
this very often happens, it is a good plan to mark it occasionally. 

In shaping the lens, it should be held between the thumb and 
forefinger of both hands (Fig. 20) at a slight angle, turning it 
from left to right. The points and bunches should be taken off 
until you have a good oval. The lens should then be held between 
the thumb of the right hand and the forefinger of the left 
(Fig. 21). It should then be revolved with the forefinger of the 
right hand as far as possible and then picked up with the thumb 
of the left until you can get another hold with the forefinger of 
the right hand. In this way the lens can be revolved as steadily 
as if it were in a machine. If you have trouble with the lens stick¬ 
ing to your fingers, a little piece of soap can be kept handy, and 
by just touching it occasionally you will avoid this annoyance. 

The lens should be beveled a little first on one side, then 
turned over and ground the same amount on the other. Too much 
pressure should not be used, as it is better not to try to grind too 
fast. As soon as the lens is beveled on both sides, it should be 
tried in the frame for size. The screw should be taken out and 



The Making of a Mechanical Optician 


27 


the temple removed, and to bring the joints together, an old pair 
of cutting pliers having the edges drilled should be used. 

As the lens is tried in the frame, you should learn to judge 
the amount it will be necessary to grind off. In any case, how¬ 
ever, the lens should be tried frequently, so that it will not be 
ground too small. It should be fitted so that the joints just come 
together, and no light can be seen between them with the lens 
perfectly tight, and as the joints are held with the pliers in the 
right hand, try to twist the lens with the left. The level should be 
perfectly smooth, and equal on both sides, with no chips or bright 
places; if it does not come out this way the lens was cut too small. 
Just before trying the last time, the lens should be held in the 
right hand between the thumb and forefinger in a vertical position, 
and allowed to turn on the stone a couple of times to take off the 
sharp edge, otherwise it will chip when the joints are screwed up. 

When the lens is placed in the frame see that the strongest 
concave, or weakest convex surface, is next the eye, so that the 
axis will be right (the lens should have been cut this way). Also 
see that the ends of the lens come to the center of the joints and 
foot of the bridge. Never mind if the frame is out of shape, put 
the lens in right and true the frame so that the lenses will be hori¬ 
zontal afterward. In grinding the lens for the other eye care 
should be used to keep the shape the same. 

When grinding torics, coquilles and strong lenses, the frame 
should be curved slightly to conform with the shape of the lens, 
otherwise the eye wire will spring off the bevel, causing the lens 
to drop out. Clerical, or half eyes, are difficult to grind and care 
should be used to fit the corners well before attempting to reduce 
the lens to size. After the corners and top are fitted the surplus 
glass can be ground off the lower part. 

Pebbles cannot be ground successfully on an ordinary alun- 
dum stone, as special grit is required. Carborundum is the best, 
but craigleith answers the purpose very well, although it is slow 
cutting. 

Window glass should not be ground on your stone, as this has 
a tendency to rough it. 

Strong lenses require a steeper bevel than the regular, and as 
the high power convex are thin on the ends and thick on the sides, 
it is well to start the bevel on the sides first and grind the ends 
last, otherwise the lens will be too full. 


28 


The Making of a Mechanical Optician 


In fitting lenses to rubber or zylonite frames, the frames 
should be softened in hot water or over a gas flame. Extreme 
care must be used not to burn the frame. Shell should never be 
attempted, as these are very brittle and are costly to repair. When 
fitting lenses to metal lorgnettes, it is advisable to cover the handle 
with tissue paper or cloth to prevent scratching. We advise. 



however, that these difficult jobs be sent to the prescription houses, 
as it is often expensive to repair or replace these frames should 
they become damaged or broken. 

For hand grinding the lens is cut mm. larger all around, 
and the first operation is to shape it. It is held in the center 
between the thumb and forefinger of the right hand in a vertical 
position. The left thumb and forefinger are used as a rest and 
guide (Fig. 22). The points and bunches are then ground off 
until you have a true oval. The lens is then held in the same 
position, but allowed to revolve slowly. This is done by pressing 
gently against the stone and allowing the lens to slip between the 
fingers in the right hand; the left is simply to steady and guide it. 




The Making of a Mechanical Optician 29 

Care should be taken not to let it get away from you, but with a 
little practice it can be revolved as steadily as a machine. 

After the lens is down to size and the edge is flat and smooth, 
the sharp edge should be taken oflf, or, in other words, put on a 
very small bevel. Strong lenses and torics will require more 



bevel where the straps are fitted to prevent chipping. In this 
operation the lens is held in the same position as in grinding 
lenses for frame (Fig. 21). If a new pair of lenses is being 
ground they should be measured in millimeters for length and 
width. The sizes are as follows: i eye, 37 x 28; o eye, 38J4 x 
291^ ; 00 eye, 40 x 31; 000 eye, 41 x 32; 0000 eye, 44 x 30. Full 
eyes or short ovals are the same length, but two (2) mm. wider. 

For measuring, a millimeter rule is considered accurate 
care must be used not to burn the frame. Shell should never be 
enough, but if you wish to be exact, a Boley gage is better. In 
matching a broken lens, you can lay the new one over the old one 
and judge the size, but this requires practice. The shape should 
also be noted as it is possible to grind two lenses having the same 
length and width, but the shape will be different, one may have 






30 


The Making of a Mechanical Optician 


full corners (Fig. 23) and the other pointed (Fig. 24). Some 
prefer the shape with full corners, as it gives a straighter surface 
for the strap to bear against, and, consequently, does not loosen 
as easily. 

Drop eye lenses (designated by various trade names in differ¬ 
ent parts of the country) are ground in the same manner. These 
are ground off axis very easily, so this point should be looked out 
for. Also see that the ends are not ground too quickly, as the 
shape will lose its identity and the results will be more like a 
regular oval. 

For machine the lens should be cut a little larger than for 
hand grinding, usually about i mm. all around is allowed. The 
marked places on the lenses for cutting are used to center the 




lenses in the machine. The lenses are placed in the centering 
device with the cutting lines, together with a piece of rubber or 
wet cardboard between them to keep them from slipping. Ex¬ 
treme care must be used to see that these are placed on the pads 
just right*so that the axes and centers will be perfect. A little slip 
at this point will spoil your lenses. 

For size subtract the width from the length and the differ¬ 
ence will indicate the number of the pattern to be used. This is 
placed in the machine and the gage set to the length required. 
For example, to grind 40 x 31, the difference is 9. Fit this pattern 
and set the pointer to 40 mm. 

After the lenses are in position start the machine and let the 
lenses down to the stone. Do not put much tension on the spring 
until the lenses have revolved two or three times, taking off the 
roughness. As soon as the sharp points are ground off the ten¬ 
sion can be increased so that they will grind faster. 


The Making of a Mechanical Optician 31 

The tension should also be regulated according to the number 
of lenses grinding at a time. If too much is used for a single lens 
it will chip. The time necessary to grind a pair of lenses will vary 
from four to ten minutes, depending on the thickness and the 
amount allowed for grinding. Plenty of time should be given, 
however, because if they are removed before they are finished, the 
shape will be irregular. You can easily tell when they are finished 
by the sound. It is unnecessary to remove them immediately, how¬ 
ever, as they can grind no smaller than the gage. After they are 
ground to size they must be removed and the sharp edges taken 
off the same as if ground by hand. 

When the lenses are removed from the machine, they should 
be wiped immediately, or the grindstone grit is apt to dry on the 
surface, and when cleaned off it leaves marks resembling 
scratches. These are very difficult to remove, but they will come 
off with a wet cloth and fine pulverized pumice. 

Lenses can be edged in the machine without cutting if de¬ 
sired, but this is of no advantage unless grinding for stock. Some 
opticians prefer to use their machines this way rather than allow 
them to stand idle, but there is no advantage in it, as interchange¬ 
able lenses can be obtained of the jobbers at about the same cost. 

The greatest difficulty experienced in grinding by machine is 
the slipping of the lenses. This is caused by the pads becoming 
soft and greasy. It is a good idea when through with the machine 
for the day to place a piece of blotting paper between them to 
absorb the moisture and prevent sticking. 

When placing concave lenses in the machine make sure that 
the pads between the lenses are thick enough, otherwise the edges 
will touch, causing them to crack. 

If flat places or lines, called facets, are found on the edge, the 
stone is out of true and should be turned immediately. 

Some prefer to use the frameless machine without a pattern, 
and when grinding this way the lenses must be watched to see 
that they are not ground too small. This method is perhaps 
quicker, but the machine requires constant attention. 

In cutting, twice as much should be allowed on the ends as on 
the sides (unless your machine has a compensating device). For 
example, to grind 40 x 31, the lens should be cut 41 x 31^^. 

Providing you do grind nearly all your lenses by pattern, it is 
often convenient to match odd or special shapes by this method. 


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CHAPTER IV 


Drilling and Mounting 

Glass can be drilled in various ways, either with a hand drill 
or with power; with steel point or diamond; in an upright drill 
or in a lathe. 

For drilling, a diamond is recommended, and this can be 
obtained in a white splint, carbon (black diamond), white turned 
diamond, or a turned carbon. A white splint costs about five 
dollars,' although a better one can be obtained from six to eight 
dollars; carbon about ten dollars; white turned diamond about 
twelve dollars; turned carbon from fifteen to eighteen dollars. 
We recommend, however, the best white splint, as it has a rough 
point and cuts faster. It can also be sharpened at a less expense. 
Turned diamonds do not cut as fast, but are less liable to break. 
By using care, however, one need never break any diamond. 

A diamond drill should run at from 1600 to 2200 revolutions 
per minute, but 1800 is recommended. If it runs too fast, 
it throws the lubricant out of the hole, and, consequently, runs 
dry. If it runs too slow, too much pressure is required. These 
two points are really the cause of all breakage. 

Before starting to drill, see that the stop is set so that the 
drill point just clears the pin on which the lens is placed. There 
should be just space enough to slip a card easily under the drill 
point. The gage should also be set so that the hole will be the 
right distance from the edge. For regular flat lenses this distance 
is .093. Strong convex lenses will be drilled farther in, and 
strong concave lenses nearer the edge. 

All lenses should be drilled, however, for a snug fit and then 
broached or filed the least bit for the variations of the strap. The 
most accurate way is to try the strap on the lens and mark it in 
the screw hole with ink, or better still, with a sharp steel point. 
(This can be made from an old rat tail file.) In most of the large 
shops the drills are arranged so that the pressure is applied by 
foot power, thereby allowing the use of both hands. This can 
be arranged very easily by drilling a hole through the bench and 


33 



34 


The Making of a Mechanical Optician 

attaching a wire to a foot pedal on the floor. After a little prac¬ 
tice it will be found that the foot is just as sensitive as the hand. 

There are a great many drilling fluids on the market, and, 
as these are cheap, we would recommend using one of them 
rather than going to the trouble of making it. The theory of a 
lubricant is to keep the drill cool, and in lapidaries water is used 
on diamond drills for drilling all kinds of stones. Turpentine, 
however, is supposed to soften glass, and for this reason it is used 
principally in making these preparations; ‘‘3 in i oil is also used 
very successfully by many opticians. If you have an up-to-date 
drill, with a centering device, you will set the gage and place the 
lens in position between the four pins, apply the lubricant and 
place a slight pressure on the handle. Do not drill right straight 
down, however, but raise the drill constantly to allow the lubricant 
to flow into the hole. If it runs dry it will show a white powder 
and more fluid must be applied. This is the most particular point 
in drilling and must be watched constantly. ‘ The breaking of a 
drill is usually due to carelessness. 

If you find that the lens has a tendency to vibrate, the point 
of the drill is out of true and should be attended to immediately. 
This is due to the breaking off of a small part of the stone, making 
the point out of center. This can be sharpened, however, pro¬ 
viding the point is not too short. When buying a new drill, be 
sure that the setting fits the hole in the spindle perfectly. If it is 
small the set-screw will throw it out of center. 

After the lens is drilled half way through, turn it over and 
drill from the other side. If it is drilled above center it will be 
necessary to change the gage governing the center device to the 
opposite side. 

Tories cannot be drilled in a regular centering device unless 
it has a tipping table or other attachment to tilt the lens. If a 
drill is used without an attachment of this kind, the centering 
device should be removed and the lens held in the hand. The 
lens should be tilted up when drilling the concave side, and down 
on the convex. 

Lenses can be drilled just as well without a centering device, 
but it is necessary to dot the lens. This can be done by the eye, 
or a separate centering device for marking can be obtained for a 
small sum. 



The Making of a Mechanical Optician 35 

A steel point will drill just as good a hole as a diamond, but 
it is necessary to sharpen it after drilling every few holes. A 
good point can be made from an old rat tail file sharpened to a 
long point, having two rounded sides. In grinding, however, be 
careful not to draw the temper. A steel drill should run much 
slower than a diamond, or from 600 to 800 revolutions per minute. 
The centering device should not be used, but the lens should be 
held in the hand, and, instead of being held rigidly, it should be 
rocked slightly to allow the drill to cut. 

After you have drilled both sides of the lens so that the holes 
meet, it should be broached out. For this purpose a regular four¬ 
sided steel broach is used, and is fitted in one end of the idler 
shaft. These will have to be replaced occasionally, as they become 
dull and break the lenses. Some drills are supplied with a broach, 
similar to a rat tail file, but these are used in the same way. 

Hand drills are not as satisfactory as power drills, but are 
used successfully, however, by opticians wishing to drill occa¬ 
sionally and who have no power. We recommend running these 
by a foot wheel, as better results can be obtained. The great 
difficulty with these drills is that you cannot get speed enough, 
and although a slow speed will do for a steel drill, it does not 
work well with a diamond. When using them, however, more 
time must be allowed for drilling, as it is not well to force it. 

We frequently hear of cases where opticians require from 
three to five minutes to drill a hole. In cases of this kind there 
IS something wrong; either the speed is not right or else the 
diamond needs sharpening. If a drill is working right a hole can 
be drilled in five to ten seconds. 

Opticians often make the mistake of using a very long dia¬ 
mond drill. This is not necessary, and they are very liable to 
break. It is much better to use a short one for all ordinary lenses 
and have an extra one for thick ones. Do not forget that dia¬ 
monds are not guaranteed against breakage, and if you get one 
that is not right, exchange it at once. 

For mounting, the following tools are needed: A pair of 
No. 35 strap pliers, snipe nose pliers, cutting pliers, a rat tail file, 
glass screw tap, tap holder or pin vise, fine flat file, a screwdriver 
with a swivel top and a bottle of drilling fluid. Before trying the 
lens in the strap it will be necessary to remove the screws from 


36 The Making of a Mechanical Optician 

the mountings, and as these are inserted at the factory by machine, 
they will probably work hard. The screw holes should then be 
tapped out so that the screws enter easily. 

After the holes in the lens are drilled and broached and the 
studs tapped, the next operation is to try the strap on the lens. 
If the lens is thinner than the strap it will fit into the bottom of 
the strap. Notice whether the parts of the strap that bear on the 
edge conform with the curve of the lens. If not, shape them 
with the snipe nose pliers. Then take an old tap or a pin about 
the same size and insert it in the screw hole so that it passes 
through the glass into the screw hole of the opposite strap. If 
the lens has been drilled properly, it will be just a little too tight. 
Now remove the glass and file the hole just a grain toward the 
edge of the glass with a rat tail file lubricated with drilling fluid. 
Insert the lens again and try a second time. If an old tap is used 
it acts the same as a screw, so that when it is screwed into the 
hole you can easily judge whether it is too tight or not. If it 

I .-^g as 

Fig. 25 

appears the least bit tight do not try to force it, but remove it and 
file the hole a little more. For this reason a small metal screw¬ 
driver, with a swivel top, is recommended, rather than a wooden 
handle one, as you do not get such a good purchase on the screw. 
You can then tell readily if it binds. One of the greatest mistakes 
is made in forcing screws in the mountings, as this is responsible 
for most all the breakage. 

When the tap enters the hole easily and there is no play, the 
screw can be inserted, and as it is turned in try the strap and see 
if it is tight. When a strap is properly fitted it should be possible 
to twist it sideways just a little until the last turn of the screw, 
or until it is set up. The last turn should make the snug fit. If 
the screw turns hard from the start, the hole in the glass should 
be filed a little more. 

We have now taken it for granted that the lens and strap 
were just the right thickness (Fig. 25). If the strap is too 
narrow the lens, perhaps, will go in but half way. We then take 
the strap plier and insert the plain jaw in the strap and the jaw 




The Making of a Mechanical Optician 


2>7 


with the hook on the outside (Fig. 26). With a slight pressure 
the strap will be widened a little, and if the lens is still tight 
repeat the operation on the other side of the strap. This opera¬ 
tion was formerly done with a snipe nose plier before the inven- 



Fig. 26 Fig. 27 


tion of the strap plier. The great difficulty experienced with this 
tool was that the straps were thrown out of alignment and it was 
necessary to square them up and tap them over again. With the 
strap plier this is not only unnecessary, but the work can be done 
much more quickly. 

If the lens is thinner than the strap the plier is inserted with 
the hook on the inside and the plain jaw on the outside (Fig. 27). 
This will make a slight kink in the strap, very close to the lens¬ 
bearing parts, which is hardly noticeable. In selecting straps, 
however, it is best to use one that is a little snug and open it with 
the strap pliers than to use one that has to be made much nar¬ 
rower. A convex lens is, of course, thicker at the screw hole 
than at the edge, and for this reason the strap will be made nar¬ 
rower at the bottom (Fig. 28), otherwise it will twist sideways. 
A concave lens is just the opposite, and the strap should be made 
narrower at the screw holes with a snipe nose plier. The lens 
should be inserted on the side at the thinnest part and slipped 
along to the screw hole. In fitting strong lenses, especially con¬ 
cave, see that there is a good bevel on the edge near the screw 
hole to prevent flanking. 

If the hole has been drilled too near the edge it will be 
necessary to bend down the lens-bearing parts and a little varia- 



Fig. 28 


tion does not matter materially, but if there is any space to speak 
of these ears should be bent with a slight kink near the post (Fig. 
29). This can be done with the strap pliers, but care should be 
used not to take up too much. Under no circumstances bend the 





























38 


The Making of a Mechanical Optician 


points down, leaving an opening between the lens and the strap 
(Fig. 30), as this will work loose almost immediately. In some 
cases where the strap has been opened as much as it will stand 
in fitting strong concave lenses, or if the workman does not have 



a pair of strap pliers, it will be necessary to file the edge of the 
lens to allow it to go into the strap, but this method should not 
be used unless absolutely necessary. It is, however, desirable to 
do this on strong concave lenses. 



In fitting torics the strap should be bent with the snipe nose 
pliers to conform to the curve of the glass (Fig. 31). Although 
this is really no more difficult, most opticians prefer to send the 





The Making of a Mechanical Optician 


39 


mountings to the prescription houses and have these lenses 
mounted, as the lenses are expensive, and if one is broken it takes 
away the profit. Occasionally an old pair of lenses is sent in to 
be fitted with new mountings and the holes are so large that it is 
impossible to fit a strap so that it will look well. In cases of this 
kind a plug of tinfoil or of wood can be inserted in the hole 
nearest the edge of the lens and this will take up the space 
between the lens and the lens-bearing parts of the strap. There 
are also strap tighteners on the market for this purpose. 

There is also a device on the market supposed to prevent 
breakage and this is used when fitting expensive lenses, such as 
fused bifocals. This consists of a rubber tube and a glass screw, 
with a long pin on the end of the threaded part. After the screw 
is set up it should be cut off and finished. If a screw finisher is 
used the end should be left a little long to allow for rounding. 
If it is cut too short the tool will cut into the strap. If you do 
not use a screw finisher, cut the screw fairly close and file the 
end with a flat file almost down to the strap. A piece of card¬ 
board, or a brass plate having a square place cut out for the strap, 
should be used to lay over the glass to prevent the file from 

Fig. 31 

scratching. There is also a new plier on the market for this work 
which cuts the screw so close that it does not require filing. 

If the optician does his own drilling he can, of course, drill 
lenses to suit himself. There are, however, a great many who 
order lenses drilled and do the mounting themselves. Many of 
these opticians believe that lenses should be drilled so that all that 
is necessary to do is to screw them into the mounting. If lenses 
were drilled this way a great many would fit too loose, and a 
poor job would be the result. The right way is to have them all 
a little snug and then fit them as before described. To do this 
a complete set of tools is necessary and care should be used in 
fitting. If the optician would only realize that men doing the 
mounting in prescription jobs are the most expert optical work¬ 
men and have spent years learning the trade, there would not be 
very many complaints regarding the drilling. 




40 


The Making of a Mechanical Optician 


The mounting of frameless lenses is a trade in itself and too 
much care cannot be used in selecting the thickness of lenses and 
straps. The strap plier has simplified the mounting of frameless 
lenses wonderfully and some opticians have a wrong idea of this 
tool. It is not only designed to bend a strap from 2 mm. to 4 mm., 
or vice versa, but it should be used in place of the snipe nose plier 
in fitting almost every lens. In large shops the men mounting 
rimless work have two pairs, one with a short hook for the regu¬ 
lar jobs and one with a long hook for extreme cases. 


I 



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CHAPTER V 


Bifocals 

Bifocals have occupied the attention of opticians for the last 
few years on account of the wonderful improvements. Although 
the fused bifocals are the latest, it is quite a proposition to make 
them. Consequently, about the only style that the ordinary op¬ 
tician can make is the cement. 

CEMENT BIFOCALS 

In making cement bifocals the distance lenses are ground 
the same as usual, except that when grinding to frame they should 
be left a little large, or about i mm. between the joints. The 
wafers are about 30 mm. round in the rough, and if the prescrip¬ 
tion is such that one wafer can be used for two, it should be split 
in the center, using a hand diamond or a sharpened rat tail file. 
They can, however, be edged in quantity in the frameless machine 
before splitting, but care should be used not to screw them in too 
tightly. It is not practical to attempt to edge less than a pair. 
If ground in this way they will be left 28 mm. diameter and then 
cut in the center. 

It is always advisable to center wafers when possible, and if 
the prescription reads, for example, distance 2, reading + 
the power of the wafer is equal to the distance. As a spherical 
lens is practically two prisms with the bases together, by fitting 
the wafer with a thin edge upward and the thick downward, the 
prismatic power is neutralized (Fig. 32). When the power of 
the wafer is stronger than the distance, it is necessary to cut it 
nearer the center to obtain less prismatic power, consequently 
two wafers must be used. When the power of the wafers is 
weaker than the distance lens, it will be cut as far from the center 
as possible, to obtain all the full prism power. 

It is, however, practically impossible to vary this very much, 
as the wafers are not large enough. The only way that this can 
be obtained is to grind prism wafers. It is not absolutely nec¬ 
essary to do this as a little variation in the center does not matter 


43 



44 


The Making of a Mechanical Optician 


much except that the centers must always be on the same hori¬ 
zontal plane. In other words, do not have one center up and the 
other down, as one wafer centered and the other not, as this will 
cause the patient quite a little discomfort perhaps, and when they 
return, complaining, you will be at a loss to know the cause of the 
trouble. 

When fitting piano wafers to cylinders with the axis at 90°, 
always cut them from the center (Fig. 33). 

After the outside edge is finished (leaving the bottom rough) 
it is ready to be cemented. Clean the distance lens and the 
contact surface of the wafer carefully with alcohol. Put a 
small drop of cement on the lens and place the wafers in position. 
Hold the lens over an alcohol flame, or if gas is used, a Bunsen 
burner. Do not use a white flame, as it will smoke the lens. An 
ordinary wood spring clothes pin is very convenient for holding 
the lens, or tweezers can be used. Heat the lens gradually until 
the cement boils, then remove it from the flame and allow it to 
cool; at the same time place the wafer in position with a stick 
or tweezers, being careful to press out all bubbles. When it is 



Fig. 33 


Fig. 33 


cool, see that it is firm and cannot be moved. If so, the cement 
was not cooked enough. If it appears yellow when laid on 
white paper, it is cooked too much and burned. 

There is another method of cementing where the cement 
is prepared first and in this way it is necessary to cook a quantity 
of cement in a jar slowly. It requires quite a little experience 
to get this just the right consistency. The cement should be 





The Making of a Mechanical Optician 


45 


cooked so that it is quite thick, applying it to the lens with a stick. 
With this method it is only necessary to warm the lens and spread 
the cement evenly over the surface as though it was ordinary 




liquid glue. The wafer is then placed in position and allowed 
to cool. 

Strictly speaking, all wafers should be set in i mm. toward 
the nasal side, although this is not necessary when using large 
wafers. The smaller styles, such as the horseshoe shape, should 
be cemented in this way. 

CONCAVE BIFOCALS 

In making concave bifocals the wafers should be cut so that 
the thickest part is upward (Fig. 34). This is to neutralize the 
prismatic effect of the distance lens. After the wafer is properly 
placed and the lens is cool (Fig. 35), the lower edge can be cut 
off, using a pattern the shape of the distance lens. It is then 
beveled, if for frame, and ground down to size; if for frameless, 
it is ground to conform to the shape of the distance lens and 
beveled slightly to take off the sharp edge. 

The lens should then be cleaned with alcohol, or naphtha 
if preferred. If it is* then found that the cement has started, 
warm the lens slightly and the spots will probably disappear. 

FRAMELESS CEMENT BIFOCALS 

In making frameless cement bifocals it is a good plan to 
drill the lenses before cleaning, as this prevents the drilling fluid 









46 


The Making of a Mechanical Optician 


working under the wafer. Wafers should always be fitted to 
frameless lenses if possible before drilling, as there is less liability 
of cracking. Opifex bifocals are a form of cement, but the wafer 
is ground by a patented process so thin that they cannot be edged 
by hand. They are transferred directly from the block to the 
surface of the lens and cemented by electric heat. These must 
be ordered of the prescription houses, although the distance 
lenses can be ground and sent in to have the wafers fitted. There 
is little saved in this way, however, so it is just as well to order 
the lenses complete. 

A wafer having the same appearance can be ground from 
a regular wafer, and this is called the horseshoe shape. It is 
no more invisible, however, on account of the thickness. If 
special wafers are ground for this purpose as thin as possible, 
and from 22 to 25 mm. diameter, it is possible to make a very 
fair job. The prescription houses usually charge 50 cents extra 
over the regular cement price for these lenses. The best way 
to handle these is to stick them to the end of a stick, about the 
size of a pencil, with sealing wax. They should be edged carefully 
to 18 mm. diameter. They are then cemented to the distance 
lenses in the regular way, but so that the top will be 2 mm. 
below the center of the distance (Fig. 36). After the lenses 
are cool, the bottom is cut oil and ground, as usual. There is an 
occasional'call for round wafers, usually about 10 mm. diameter. 
These can be ground in the same way, but cemented to the 
distance about 2 mm. from the lower edge (Fig. 37). Oval 
wafers are also ground in the same way. 

PERFECTION BIFOCALS 

Perfection bifocals are made by grading out the lower por¬ 
tion and inserting the reading lens. The distance lens is first 
ground to size and the lower part cut with a hand diamond and a 
round pattern. It is then carefully broken out and ground on a 
small alundum stone. These stones can be obtained to fit any 
buff head and in any size. The regulation shape is one inch 
diameter, although occasionally, when a larger lower is desired, 
1 % inch is used. The lower lens is then cut the same shape and 
ground on the regular stone to fit this curve. Although these 
can be ground into the frames separately, it is better to stick 


The Making of a Mechanical Optician 


47 


them together with white sealing wax. If this method is used, 
the wax must be left in (and this is no objection). If cleaned 
out the lens will be too small for the frame. 

Grooved Perfection bifocals have been used to some extent 
and the advantage claimed is that the parts are interchangeable 
and can be made up from stock very quickly. The line between 
the distance and reading is quite conspicuous, however, and for 
this reason they have never had a large sale, especially since the 
demand for invisible bifocals. 

The distance lenses can be ground the same as the regular 
Perfection, except that the curve is beveled instead of flat. This 



Fig. 37 


Fig. 36 


can be done on the small stone without any difficulty. The lower 
part is then ground flat to fit the curve of the upper and a groove 
made with a rat tail file and drilling fluid. 

Perfection bifocals are rarely used except in cases where a 
patient is obliged to work near heat and cannot afford the fused 
lenses. It is also impractical to make them in frameless. 


SPLIT BIFOCALS 


split bifocals can be centered or not as you prefer. Or¬ 
dinarily they are not, and when ground in this way the four pieces 
can be cut from two lenses, providing the power is the same in 
both eyes. The lenses are first split in the center and the straight 
edges ground on the side of the stone. Composition stones are 
molded and the sides are usually smooth enough. If not, the 
right side should be honed the same as the face. If a Craigleith 
is used the side will have to be turned true with a diamond and 


48 


The Making of a Mechanical Optician 


honed with a piece of Craigleith. When the straight edges are 
ground and beveled slightly to take off the sharp edge, they 
should be stuck together with white sealing wax. They can 
then be handled as one lens and cut to size with a pattern. They 
are also ground the same as any lens. These lenses can also be 
ground separately if desired, but it is more difficult to hold them 
when trying in the frame. If centered lenses are required the 
halves should be cut from the center of the lens and a pattern 
having this shape will be required. 

Whole bifocals are surface ground and are treated the same 
as an ordinary lens when ground to size. These are not recom¬ 
mended on account of the prismatic effect. 

FUSED BIFOCALS 

Fused bifocals are a surface-grinding proposition and will 
be described under that heading later. The blanks can be obtained 
and if care is used it is not difficult to surface them. At present, 
however, we will suppose that you prefer to buy them uncut and 
edge them yourself. When ordering them from the jobbers, 
full information must be given, such as distance and reading 
powers, diameter and height of reading portion, axis, frame or 
frameless, if reading part is to be set in and size of eye. When 
the lenses are received the axis should be marked and a cutting 
line drawn. The reading portion is then dotted with ink around 
the edge so that the circle can be seen easily. The usual diameter 
is i8 mm., and the height is within 2 mm. of the center. After 
the axis and position of the disk is inspected the lens is cut by 
pattern. Although these lenses can be edged by machine, it is 
recommended that they be ground by hand. The position of the 
disks can then be watched and there will be less liability of spoiling 
them. Also be particular that the disk is not scratched as flint 
is much softer than crown glass. In edging these lenses the disks 
should be first considered; that is, the shaping of the lens should 
be done on the lower edge first to make the disks the same height. 
After these have been made just right, proceed to shape up the 
other part of the lenses. In making the various combinations 
it is necessary to use flint of different indices and some of these 
grind quite hard. For these lenses Craigleith stones will be 
found more satisfactory. 


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CHAPTER VI 


Bridge Bending and Truing 

Bridges can be bent before or after mounting, and, although 
there is really no preference, some opticians obtain better results 
one way and some another. When bending an unmounted frame¬ 
less bridge, or a frame before the lenses are inserted, gripping 
pliers can be used to hold the strap or eye wire so that the opera¬ 
tion is simplified. An experienced person, however, can bend 
just as well after mounting, but the bridge must be held in the 
fingers. Under no circumstances should the spectacles be held 
by the lenses as they will surely be broken. 

Bridge bending is not hard to learn, but simply requires 
practice and a good eye. It is discouraged at the first attempt, 
and the reason is that the beginner starts to bend some frame to 
certain dimensions, probably selecting a difficult one, and possibly 
one that could not be bent successfully anyway. In starting 
this work, select some old frames of soft metal, such as German 
silver or Roman alloy, as these make the best frames to practice 
on, and always have some dimension to work to, as nothing can 
be accomplished by bending at random. 

For the first operation take a frame, say 6o mm. P. D., and 
bend it to 58. This is done by holding the bridge with a pair of 
No. 36 pliers in the left hand and gripping the shank of the 
bridge with a pair of round or snipe-nose pliers about half way 
from the eye wire to the turn, and, with a slight twist to the 
right, the eye is bent toward you (Fig. 38). Then grasp the 
shank near the eye wire and bend the eye back, and you find that 
the shank has the desired bend and the eye has been thrown in 
quite a little. The amount, of course, depends on the twist. 

After bending this to the required P. D., bend it back again 
to the original shape. This will give you practice in widening 
the P. D. This is accomplished by straightening the shank with 
a pair of snipe-nose pliers; in other words, take out the curve 
known as the 47 style. In this operation the eye is thrown for¬ 
ward and it should then be brought into line with the No. 36 pliers. 


51 



52 


The Making of a Mechanical Optician 


A frameless bridge is bent the same way, except that it is 
necessary to have different pliers to hold the strap, and for this 
purpose the No. 39 angling pliers are the best (Fig. 39). 

Next try raising and lowering the bridge. This is done by 
holding the eye-wire with the No. 36 pliers or the snipe-nose in 




the right hand and, grasping the crest of the bridge with the 
thumb and forefinger of the left hand, bending it up or down. 
This, of course, changes the angle of the crest a little, also the 
inset or outset, still it is the first step necessary (see Fig. 40). 

If you desire to lower the bridge and keep the angle the 
same, bend the bridge down, as described in Fig. 40, then grasp 




the frame with the No. 36 pliers (if frameless, the No. 39 pliers) 
in the right, and the shank of the bridge with a flat-nose pliers 
in the left hand, bend the shanks downward (see Fig. 41). It 
is impossible to raise the bridge and keep the angle of the crest 
and the inset or outset the same, except by shortening the shanks, 
and this should not be attempted until the first operations are 
mastered. 












53 


The Making of a Mechanical Optician 

To widen the base take a pair of flat, or snipe-nose pliers, 
and place a piece of cloth between the jaws to prevent marring" 
the bridge, and flatten it to the required measurements and shape ; 
then straighten the frame and you will find that the bridge is 
right, but the P. D. is wide. The shank can then be bent, as 
explained before, to shorten the P. D. 

To increase the outset it is necessary to shorten the shanks, 
and it is quite difficult to do this without marring the stock, but 
if you go slow, bending a little at a time, this can be done all 
right. The first operation is to grasp the bridge with the thumb 
and forefinger of the left hand and, with a pair of round pliers 
in the right hand, gradually open up the turn, beginning with the 



small end of the pliers and gradually sliding the bridge toward 
the larger part of the pliers (see Fig. 42). After this has been 
spread sufficiently, grasp the shank a little way from the turn 
and bend the eye straight, at the same time pulling forward on 
the bridge with the left hand. This pulls a little of the stock in 
the shank into the arch. It can then be trued up and the 
operation repeated on the left side. 

To decrease the outset or increase the inset the shank 
must be lengthened and the first operation is to open the turn 
of the shank a little, as before, but, instead of grasping the 
shank back from the turn, grasp it near the turn, or, if possible, 
in the turn, bend the eye straight and true up. Repeat the opera¬ 
tion on the left side. 

After practicing with the sample frame select a good frame 





54 


The Making of a Mechanical Optician 


to bend to measurements. The principal part of selecting frames 
for prescription jobs is in using good judgment, and you should 
train yourself to judge whether a frame can be bent to the 
dimensions required or not. If you do not learn this you can 
never learn to bend and will spoil stock, also waste time. In 



selecting a frame try and get everything right but one dimension, 
if possible, and it is best to change the P. D., as this is easier 
than anything else. Do not take up a frame at random and 
expect to bend it to fit the required dimensions, but study it 
carefully and learn to judge it before touching it with the pliers. 

After the lenses are mounted they must be trued up, and, 
if the bridge has been bent previously, it is a very simple 
operation. If it has not been bent it is best to straighten it 
somewhat and lay it on the pupilometer to get an idea of what 
is to be done. The first operation is to get the lenses in the 
same plane, so that they will lay flat. Then turn the spectacles 
over, holding them endwise and sight across the outside surfaces. 
The four glass screws should then be brought into line (Fig. 43). 
The spectacles should then be measured for all dimensions and 
any necessary alterations made at this point. 

We now suppose that the front is correct and true, and the 
attention turned to the temples. First straighten and true them 
so that the curve will be uniform. Then hold the front endwise 
with the temples upward, and in almost every case they will be 
found with one angled one way and the other in the opposite 
direction (Fig. 44). A pair of parallel jaw pliers (No. 40) 
should then be used to grip the endpiece close to the strap or 
eye-wire, and, with a pair of snipe-nose pliers, the joint is angled 
to make the temple perpendicular (Fig. 45). The temple is 









The Making of a Mechanical Optician 


55 


then shut down, and, if it is not in line with the endpieces, it is 
turned to the right or left, both pliers being used in the same 
position. This operation is then repeated on the other joint. 
If the front is to be angular, the joints are tilted in the same 
manner. 

Should it be necessary to set the temples back, the tip can 
be filed at the joint if gold or steel, but in gold filled it is better 
to hold the joint with a pair of pliers and pull the temple outward 
with the fingers. Although one may be broken occasionally, it 
saves filing the gold, which is very important when handling 
filled goods. There are no pliers on the market for holding the 
endpiece in this operation, but they can be made specially for 
any make or style of joint. 

In truing eyeglasses there is very little to be done except 
to straighten the lenses so that they are in the same plane, and 
adjust them so that the droop will be right. This is a very 
important feature and many opticians do not understand that an 
eyeglass should be placed as far back on the nose as possible. A 
great many times a patient requests that the spring be tightened, 
when in reality it should be opened more to allow the guards to 



go back farther. Each time the spring is tightened the glasses 
are thrown farther forward and, finally, they will grip only on 
the very edge. Now, in truing, the lenses are allowed to droop 
a little so that when placed on the nose they will be horizontal. 
If they were in this position before placed on the face, or if the 
guards are not spread enough, the lenses will set upward. This 





S6 


The Making of a Mechanical Optician 


not only looks badly but the lenses will be too high. A great 
many times eyeglasses are sent to the prescription houses for 
drop studs or guards to set the lenses lower, or even for new 
lenses drilled above center, when all that is necessary to make the 
glasses right is to droop the lenses a little more. 

When lenses are drilled above center they must always be 
turned down. For this operation grasp the stud with a pair 
of stud pliers in the right hand and hold the spring with the left. 
By bending the spring away from the lenses it will give them 
the required droop. Then take hold of the studs with both hands 



and open the spring a little until the lenses appear to be in about 
the right position. The guards should then be adjusted so they 
are parallel. 

For truing a fingerpiece mounting use the No. 40 pliers, 
placing the jaw marked “top” with the large hole over the head 
of the screw on which the spring is coiled. The lenses can then 
be changed to any position without damaging the mounting 
(Fig. 46). 

When it becomes necessary to drop the lenses in an eyeglass 
frame to make them lower on the face, the screws should be 
loosened in the end-pieces and the lenses twisted so that they set 
upward considerably. Then grasp the studs with the stud pliers 
in the same manner as before described for frameless, and twist 
the eye downward, etc. If the lenses need to be raised, they 


The Making of a Mechanical Optician 57 

should be twisted downward in the frames, the studs grasped 
with the stud pliers, and the spring bent backward toward the 
lenses, thereby raising the eye to the required position. This is 
another case that occurs frequently in prescription work where 



frames are ordered with studs above center. If the lenses are 
fitted, they can be adjusted easily and no explanation is required; 
but if the frames only are ordered, it is almost impossible to shape 
them so that they look right, and, even if this is possible, the 
optician can easily change the position in fitting them up. 

Toric lenses can be adjusted so that they curve slightly to 
conform to the features. If there is too much curve, however, 
it may be objectionable to the patient. It is well to remember 
this point, as frequently people complain that they are unable 



to wear torics, and, if the glasses are adjusted so that the angle 
is changed, it makes them entirely satisfactory. 

This also applies to the angle for reading, but not so much 
with torics as flat lenses. According to theory all glasses should 
be angled slightly, and the amount depends somewhat on the 
features. 









^8 The Making of a Mechanical Optician 

Lenses should never be drilled below center. If the spectacles 
are too low on the face, the bridge can be altered to raise them 
even if it is necessary to make one to order. It is seldom that a 
regular bridge cannot be used by dropping the shanks. 

If eyeglasses are too low they should be raised by changing 
the guards to some other style. In many cases a regular offset 
guard with a short blade will accomplish this result. It should 
be remembered that to raise the lenses the guard should be lower, 
and to lower the lenses the guards should be higher. 

There are so many guards on the market that it is well to 
look the common styles over, and it will be noticed that the arms 
are set very differently on different styles. If one is familiar 
with these styles it is a very easy matter to select a different one 
to accomplish whatever result is required. When there is diffi¬ 
culty in fitting glasses so that they will be low enough, the drop 
eye lenses sometimes are a great help, especially when the eyes 
are deep set. 

In truing temples do not leave too much curve to them, but 
have them so that they will be straight to the turn so that all the 
curve will be behind the ear. The right way to fit a temple is 
to make quite a sharp turn at ear (Fig. 47). These not only prove 
more comfortable but they look better. When the nose is sensi¬ 
tive, cylinder bridges, cork or shell nose guards can be used, but 
when fitting the latter the bridge must be somewhat higher to 
allow for the thickness of the cork or shell. 


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CHAPTER VII 


Surface Grinding 

Surface grinding is, in reality, a separate branch of me¬ 
chanical optics, for the reason that few opticians doing their 
own work attempt to do this work. Usually an optician puts in 
a plant to do his own edging, and for this part of the work he 
has time enough, but it is not practical to attempt to surface 
the few odd combinations that he may be called upon to supply 
and attend to his trade at the same time. The right way is to 
install the outfit for edging, and, as his work increases, he can 
afford to hire a man for this part of the business. He can then 
install the surface plant for the accommodation of his customers 
or for the advertising feature. 

It requires very little time to grind an ordinary lens if the 
workman is efficient, and it often saves a delay of twenty-four 
to thirty-six hours if it is necessary to send out of town to a jobber. 

A surface machine can be obtained for $58.50 and upward. 
The simple machines have one speed, and although this is suffi¬ 
cient, it is often convenient to have two speeds (Fig. 48). If 
one speed only is used, 900 to 1200 revolutions per minute are 
most satisfactory. If two speeds are used, 600 and 1200 are the 
most common. 

A lens can be ground using almost any speed, but, of course, 
the higher the speed the faster the grinding, although it requires 
more attention as it is also necessary to feed the emery faster. 
There is a limit as to speed, however; if it runs too fast it throws 
the emery off quickly and you then are grinding on the tool, and 
in this way nothing is accomplished. It must be remembered 
that it is the emery that grinds and not the tool. 

The electrical-driven machine is very convenient as the motor 
is enclosed in the base, and, consequently, does not require 
countershafts or belts (Fig. 49). It also not only requires very 
little power to operate it, but when the machine is stopped it is 
using no current. These machines can be obtained in direct 
current only at present. There are also automatic surface ma¬ 
chines on the market, and these can be used either by hand or 


61 



62 


The Making of a Mechanical Optician 

not as you choose (Fig. 5 ^)* Automatic work is somewhat 
slower, and most opticians having these machines use this attach¬ 
ment for polishing only. 

The tools cost about two dollars per pair and the gages about 



Figr. 48 


seventy-five cents per pair. These are not supplied with the 
machine, so it is necessary to order whatever powers will be 
needed. It is well to have each .12 to 3 D., then .25 to 8 D., then 
.50 to 14 D., and each diopter to 20 D.; also a piano and an 
extra 6 D. for roughing torics. It is also necessary to have a 
pair of gages for each power. 

Another point that must be considered is whether B. & L. 
or A. O. Co. glass will be used. If both, it will be necessary to 
have a set of tools for each, although by making an allowance 
it is possible to work very closely on one set of tools. There is 
about .03 D. difference on each diopter, and, as this is so small, 
it will come near enough up to 2 D., but above that select the 
nearest tool and polish it stronger or weaker as the case requires. 
(This will be explained later.) 





The Making of a Mechanical Optician 


63 


The index of A. O. Co. glass is 1.507 and B. & L. 1.522. 
To obtain the required radius multiply the focus wanted in inches 
by the index of refraction, — i. For example, i D. is 39.37 
inches and the index of B. & L. glass is 1.522. We would then 
multiply 39.37 by .522, which would make the radius of the 
tool for I D. 20.55 inches. This does not enter into the work in 
any way, however, unless the optician is mechanically inclined 
and he desires to make his own tools. It is simply necessary, 
when ordering tools, to state what glass they are to be used for. 

For grinding material the following grades of emery will 
be required: No. 60 for roughing. No. 100 for smoothing. No. 4-F 
for finishing and a grade of washed emery for fine finishing. 
The first three mentioned should be bought in ten-pound cans; 
the washed can only be obtained from optical concerns in five- 



Figr. 49 


pound cans. This is also very expensive, as compared with other 
grades, but it lasts a long time as it is necessary to use only a 
very small quantity at a time. It should also be remembered 
that a good finish saves a great deal of time in polishing. 

There are several kinds of grinding material on the market, 




64 


The Making of a Mechanical Optician 

such as carborundum, corundum, alundum and crushed steel, and 
these are graded about the same as emery. They cost more, but 
are supposed to cut faster and stay sharp longer, but for a single 
machine it hardly pays to mix the different materials. It should 



Fig. 50 


be remembered that the sharper or rougher the materials used 
the harder it is on the tools and they must be watched more 
carefully to see that they are kept true. For polishing, rouge is 
used, and this comes in several grades. The grade used by 
jobbers is all right and should be ordered in five-pound boxes. 
There is also a black pigment used by some opticians. For polish¬ 
ing, cloth, felt or broadcloth is most commonly used, and, although 
this can be obtained almost everywhere, it is more satisfactory 
to order it from the jobber and you will then be sure of getting 
a quality that will do satisfactory work. Pitch can be obtained 
in one-pound cans from the jobbers, and this is used to stick the 
lenses on to the blocks. It can be made easily by taking a quantity 
of resin and melting it. When it is poured off to cool, a little 
turpentine should be added to soften it, or, in other words, to 
keep it from getting brittle. In the winter it should be softer 
than in the summer, as the temperature will affect it. If it is too 
soft the glass will slide on the block in polishing, and if too hard 
it will jump off the block when chilled in water. To make it 
black a little lampblack can be added. The dark surface makes 
it much easier to inspect the lenses when polishing. 




The Making of a Mechanical Optician 


65 


A few blocks are usually furnished with, a machine, but more 
will be required. Those furnished are round and flat (Fig. 51), 
and these will do for weak power lenses. For stronger powers 
deeper holes are needed, so they are made with a lug on the back 
(Fig. 5 ^)- Some of these should have a convex face (Fig. 53) 
and some concave for torics (Fig. 54). If square blocks are used 
it will be much easier to caliper the lens while grinding. A few 
small, round blocks will also be needed for wafers (Fig. 55). 

Before fitting the tool to the machine it should be tried 
with the gage, and if it is not perfectly true it should be made 
so before attempting to grind the lens, otherwise the power will 
not be correct. A great many opticians use tools without gages, 
or, even if they do have them, they allow the tools to get all out 
of true and then send them to a machinist to be put in shape. 
This is entirely wrong and unnecessary, as it is a very easy matter 
to true the tool a little each time. The method is the same as 
trying the surface of a board to see if it is square; that is, the 
tool is held in one hand on a level with the eye and the gage is 
held perpendicular to the surface. If no light can be seen it will 
fit perfectly; if light is seen, notice whether it is weaker or 
stronger or if there is simply a high or low spot. In grinding, 
usually the tool wears on the side and the center will be high. 
For this work a piece of carborundum 8 in. long, 2 in. wide and 
I in. thick is used of a fairly coarse grade. The tool is placed 
on the spindle and run at full speed. With the carborundum 
stick it can be turned nearly as well as in a lathe. A little 
should be taken ofif at a time, however, and tried frequently 
with the gage. 

There are usually two pans furnished with the machine; 
one of these should be used for grinding and the other for 
polishing. Some rough emery (No. 60) is placed in the pan with 
quite a lot of water, enough so that it covers the emery. It will 
do no harm if there is too much as the emery will stay at the 
bottom. In roughing, this is fed on to the tool with a spoon or 
with the fingers. The No. 100 emery should be placed in an agate 
drinking cup, or something of that nature, and wet so that it 
will be in the form of a paste. The No. 4-F emery can also 
be placed in a cup of this kind, but the washer should be kept 
in a small jar or box with a cover. The rouge can be placed 


66 


The Making of a Mechanical Optician 


in a cup and wet in the same way. An extra cup of water should 
be kept at side of this, and, in polishing, this is applied with a 
brush. It will be necessary to have a large pail of water handy 
for rinsing the lens from time to time, and, after these different 
receptacles are arranged conveniently, you will be ready to grind. 

For surface grinding it is necessary to have a stock of 


X V 

Fig. 61 

rough cylinders. These come in thickness varying from 2 to lO mm. 
Those most commonly used are 2^ and 4 mm. In selecting 
the stock for any particular job it is well to caliper them, as this 
not only saves glass, but also saves a great deal of time in rough¬ 
ing. For this work a pair of calipers graduated in 1/5 mm. is 


/ \ 

I / X I 

Fig. 52 

used (Fig. 56). It is necessary to allow 2/5 mm. for each 
diopter and 4/5 mm. for each prism diopter. To this is added 
about 2/5 mm. for grinding. For example, if we are to grind 
-f I =rz -b -SOj a + -50 cylinder is selected 4/5 mm. thicker on 
the edge than the required thickness of the finished lens, thus 


JL 1 

Fiff. 53 

allowing 2/5 mm. for the curve and 2/5 mm. for the grinding. 
When grinding a convex lens the center is hardly touched, pro¬ 
viding the stock is about the right thickness at the start, but, 
unless the lens is fined down very carefully, which takes extra 
time, you cannot help grinding off a little extra glass, and, for 
this reason, a little allowance for grinding must be made. If 














The Making of a Mechanical Optician 67 

the combination to be ground were — i = — .50, a rough cylinder 
having about the right thickness on the edge would be selected 
as practically the center only is ground. The allowance for grind¬ 
ing is all that would be taken off the edge. If the combination 
to be ground were -f i = -f .50 axis 90 =: 1° in, it would be 
necessary to allow 4/5 mm. more for the prisms. For example, 
the lens when finished should be 2 mm. thickness on the edge; 
to this is added 2/5 mm. for the one diopter and 4/5 mm. for 
the prism. To this is added 2/5 for grinding and the rough 
cylinder to be selected would be 33/5 mm. For this it would 
probably be necessary to use 4 mm. stock. It should be remem- 



Figr. 54 


bered that over 4 mm. rough cylinders cost extra for each 
millimeter thickness. 

Toric rough cylinders should be purchased in molded form, 
when possible, as this saves a great deal of roughing. Most all 
blanks are made this way at the present time, but some of the 
smaller manufacturers put them out in flat form. There is also 


Fig. 55 

another point to be considered in using these lenses, and that is 
that often it is not possible to get the thickness out. In other 
words, when they are not molded, so much stock has to be ground 
out inside that it leaves the lens a knife edge. These can be 
obtained in plus and minus 6 D. base curve, also plus and minus 
9 D. base curve. The majority of combinations can be ground 
on 6 D. base, but, as the spherical power increases, it reduces 
the toric effect so that it becomes necessary to transpose the com¬ 
bination, so that it is ground on a — 6 D. base. It is preferable, 
however, to grind these combinations on a 9 D. base. For ex¬ 
ample, + 3 = + I, if ground on a -j- 6 D. base, would have but 
— 3 inside curve. If ground on a -)- 9 D. base curve it would be 
_ 6 D. on the inside. It could be transposed, however, and 









68 The Making of a Mechanical Optician 

ground on a — 6 D. base curve and it would be — 6 D. on the 
inside and + lo D. on the outside. It should be remembered 
that the base curve is always the weakest meridian on the cylinder 
side; that is, a + 6 D. base curve is + 6 in one meridian and 
stronger in the other. The difference will be the power of the 
cylinder. A — 6 D. base is — 6 D. in one meridian and stronger 
in the other. The spherical power is obtained by grinding the 
opposite side. 

Another point to keep in mind is that concave toric cylinders 
cost more than convex, and, whenever possible, all combinations 
should be transposed so that a plus cylinder can be used. For 



Fig:. 66 


example, in the combination — i = — .50, if it is ground as 
written a — .50 toric cylinder would be selected and the cylinder 
surface would, of course, be on the inside. On the outside would 
then be ground + thus making the — i sphere. If this were 
transposed to — 1,50 = + 50, a -\- .50 toric cylinder would be 
selected and — 7.50 ground on the inside to produce the — 1.50 
sphere. The reason that concave toric cylinders cost more is that 
the large factories have not as yet perfected machines for grind¬ 
ing these in quantity the same as the convex, and, consequently, 
they are ground singly at a greater expense. 

When selecting colored lenses it is necessary to have in 
mind that as the glass is ground thinner the shade will be much 
lighter, and it is a very difficult matter to judge just how they are 
coming out. For this reason colored lenses with power are al- 





The Making of a Mechanical Optician 


69 


ways expensive as a great many times it is necessary to grind 
two or three pairs before the exact shade is produced. The de¬ 
mand for colored lenses, however, is so unimportant that they 
call for little consideration as compared with the colorless variety. 

For wafers, spherical lenses are used, but always selected 
so that one surface is correct. For this Pcx. lens always work 
in nicely as the old curves can always be found. For example, 
for the combination — i = + 3.50, a -f- 2.25 Pcx. would be 
selected, and this would be on the outside + 3-50 and on the in¬ 
side — 1-25. We would then block it with the convex surface 
down and regrind the inner to — i, at the same time reducing the 
thickness to whatever is desired. 

Spherical prisms can be ground on rough prisms or a stronger 
piano prism can be used to get the thickness required. 


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CHAPTER VIII 


Surface Grinding—Continued 

The machine now being in operation, and the emery arranged 
conveniently, the first operation will be to mark the lens. If a 
brown pitch is used in blocking, black ink will show well enough, 
but if black pitch is used, white ink is much better. If a simple 
compound is to be ground, no marks are required, but with all 
prism combinations the axis must be marked. This method is 
the same as for cutting, except that it must be taken into con¬ 
sideration that when the lens is on the block, you, perhaps, are 
looking at it from the wrong side. This, of course, depends on 
the combination. For example, if the combination to be ground 
is — 50 axis 45 = 1° in, the lens can be marked with the 
cylinder in (or up, as it is laid on the protractor) just as it is 
to be fitted to the spectacle. 

It is, of course, necessary to mark all lenses on the cylinder 
side, otherwise the marks will be ground ofif. When this is stuck 
on the block the cylinder will be down, and you are really 
working on it as though the axis was 135°. On the other hand, 
if the combination is + 50 axis 45 = 1° in, it would be necessary 
to mark it as if it were to be 135°. The reason for this is that 
you are marking it on the cylinder side, and after this is com¬ 
pleted, it is to be fitted to the spectacle with this side out. The 
reason for marking is to have a line to grind the prism on, in 
other words, to tell the direction of the base. If this is to be in, 
the axis must be set at the proper angle so that the prism line 
must be horizontal. It does not matter, however, how this is 
placed on the block as long as the relative position of the axis to 
the base is correct. 

If a double prism is to be ground, that is, a lens with the 
prism out and up, etc., it will be necessary to have a line for both 
prisms. In marking, the axis is first dotted and laid on the pro¬ 
tractor at the proper angle, the prism lines are then drawn and 
the bases marked with the letter “B”. As the prism lines are 
the only ones that are considered, the axis dots can then be rubbed 


71 



72 The Making of a Mechanical Optician 

out if preferred to save confusion. There is a chart published 
for calculatipg the effect of double prisms that is very con¬ 
venient, but it is not absolutely necessary to use this in surface 
grinding. A double prism is really a single prism ground at a 
different angle. For example, a 2° up = 2° out in the right eye 
would be practically a 3° axis 135°. 

For blocking, an ordinary cheap gas stove is sufficient, but 
a piece of sheet iron should be laid over the top to prevent any 
pitch running down into the stove and clogging the holes. The 
blocks should be heated on the stove, and, when good and hot, 
should be taken off and placed on the bench. A little pitch should 
then be put on and allowed to melt. The glass to be blocked 
should be warmed slightly and laid on the block a second and 
then removed. It will be noticed that some of the pitch sticks 
to the surface. A little more of the pitch should then be put on 
the block and the lens laid on a second time, and then removed. 
In this way you gradually build up a backing for the lens. This 
operation should be repeated several times until there is pitch 
enough between the block and the lens so that it will hold 
securely, and also that there is no danger of the glass touching 
the iron. This not only prevents scratching, but if there is not 
pitch enough to form a good bed for the glass, it will crack 
when pressure is applied in grinding. 

Flat lenses do not require as much pitch as those having a 
concave surface or a toric. Ordinary concave lenses can be 
blocked on flat blocks, but care must be used to fill up the space 
with pitch for the reason just stated. For convex toric cylinders, 
a block having a concave surface should be used, and although 
the curve should be about the same, it is not absolutely necessary, 
as the surface can be built up with pitch. For concave toric 
cylinders, convex blocks should, of course, be used. After the 
lenses are blocked, they should be allowed to cool gradually. 
After they are cool, the pitch on the back of the lens that 
overhangs the block should be scraped off with a knife so that 
the four sides can be measured with the calipers. Lenses can 
also be blocked over an ordinary Bunsen burner, and if it is 
done in this way, the pitch should be moulded into sticks and 
melted on the block the same as sealing wax is used. 

We will suppose that the combination to be ground is -j- i 


73 


The Making of a Mechanical Optician 

— “h 50 cyl. and i 1/2 strap on the edge when finished. We 
have selected a -f- 50 cylinder, 21/2 mm. thickness, and have 
blocked it as described. We then select the tool to grind -|- 
I sph. This, of course, will be a concave tool to grind a convex 



Fig. 57 


surface. It should be tried with the gage to see if it is correct. 
The rough emery is already in the pan, with plenty of water. 
The block or lens is then taken in the left hand and held on the 
tool, spooning the emery on with the right hand (Fig. 57). After 
the sharp edges are ground off, the block can then be placed 
under the spindle in the handle (Fig. 5). It will then be necessary 
to adjust this so the lens is in the center of the tool. As to 
position, the grinder can stand wherever it is most natural. Some 
of the older machines are arranged so that the handle points 





74 


The Making of a Mechanical Optician 

directly to the operator, and some use it in this position; others 
stand a little to one side. In either case this is somewhat 
awkward and the best way is to have the handle run from right 
to left, so that it is in a horizontal position to the grinder (Fig. 58). 

The newest machines are made so that they can be adjusted 
to any position. When the handle has been adjusted correctly, 
the machine can be started. The lens will then revolve or spin 
on the spindle, and the grinder then moves the handle forward 
and back so that the lens will travel from the center to the edge 
of the tool. This motion is to break up the rings which would 
form on the surface of the glass if it were held in one position. 
One must be careful, however, not to run over the center of the 
tool, or the block may fly off. As the lens is moved back and 
forth, the emery should be fed continually with the spoon. After 
the lens has ground a minute or two, it should be removed, and 
if it is ground all over the surface, it is ready to measure. Now 
take the calipers and measure all four edges. If it is the same 
all around, the lens is centered and not prismatic. If there is a 
difference, take the block in the hand the same as when starting 
(Fig. 57), and grind off a little of the thick edge, then measure 
again. If found correct, it can then be placed on the spindle 
again and ground as before. 

The system of measuring should be remembered, that is, 
2/5 mm. allowance for every diopter. As we started with a lens 

mm. thick and wish to obtain a lens 1^4 mm. it will be neces¬ 
sary to grind off i mm. or 5/5 on the calipers. In the roughing 
about 2/5 mm. will be taken off, being careful, of course, to keep 
it centered as described. Do not be afraid to measure it too 
much, for it is better to take off a little at a time than to spoil the 
lens. After it has been roughed down, wipe off the tool and rinse 
the lens in water. (For this purpose, keep a pail at the side of 
the machine.) Now take the No. 100 emery, which is in the cup, 
and grind as before, smoothing the surface and taking off about 
1/5 mm. Then wipe off the tool again, rinse the lens and take 
the No. 4-F emery. This you can apply with the fingers, or a 
brush if preferred. After this grade, clean the lens and tool 
again thoroughly and you are ready for the fine finishing. For 
this operation it is necessary to use but very little of the finest 


75 


The Making of a Mechanical Optician 

emery, applying it with one finger. The idea now is to g’et just 
as fine a surface as possible to obtain next to a polish. 

Although it is unnecessary to waste the emery, all scratches 
and pits must be removed, as time is not only wasted in trying 
to polish them out, but the lens produced is not so good. It 



Figr. 68 


should also be remembered that this grade of emery is expensive. 
All through these different operations keep in mind that the lens 
must be calipered frequently to keep it from being prismatic, 
and also, that as you are continually grinding off glass, you are 
nearing the thickness required for the finished lens. Also be 
particular to clean the tool and the lens between each grade of 
emery used, as one grain of rough emery on the tool when fine 
finishing will scratch the surface. 

If the combination was — i = — 50, the operation would 



^6 The Making of a Mechanical Optician 

have been the same, using, of course, the opposite tool, but if 
the order called for a certain thickness in the center, the lens 
would be 2/5 mm. thicker on the edge. Although this has to 
be taken into consideration in convex combinations, allowing the 
lens to be 2/5 mm. thinner on the edge than on the center, it 
does not make quite so much difference, for the reason that the 
concave lens is apt to be ground through the center. This will 
be noted in grinding the stronger combinations, and one must be 
accurate in measuring when selecting rough cylinders. 

For each prism diopter 4/5 mm. must be allowed, so if the 
combination to be ground was + i = + 5^ axis 90° = 1° in, 
we would allow 2/5 mm. for the sph. and 4/5 mm. for the 
prism, making i 1/5 mm. besides the allowance for grinding. 
We have already described the method of marking for a prism, 
and the blocking is the same as for a compound. In starting to 
grind, the lens is held in the hand (Fig. 57), not on the spindle, 
as before, but we grind off the edge where the apex is to be, 
leaving the edge for the base as thick as possible. It will now be 
seen why it was necessary to mark a mechanical axis or prism 
line. It should be measured on this line, and the base should be 
4/5 mm. thicker than the apex. The two opposite sides are of 
no account, except that they should be exactly the same thickness. 
If one was thicker than the other, there would then be a prism 
power up or down as well. By this it will be seen how to grind 
a double prism. For example, if the combination was to be 
I = 50, axis 90° = 1° in and 1° up, we would have 

4/5 mm. difference on the edge between the apex and base on 
the 180° line, and also 4/5 mm. difference on the 90° line. When 
the lens has been roughed down in the hand so that the prism 
power is approximately correct, it can be placed on the spindle 
(Fig. 58) and roughed down to the proper thickness. It should 
be remembered that all the prism power must be roughed on with 
the block in the hand, and that the lens cannot be ground pris¬ 
matic on the spindle. This does not mean that the lens will 
not grind prismatic because it will grind off center more or less, 
but it means that you cannot control the direction of the prism 
power on the spindle. As different grades of emery are used, 
the edge must be measured constantly, and if there is any variation 


The Making of a Mechanical Optician 


77 


found, take the lens in the hand again and true it up with what¬ 
ever grade of emery you may be using. 

In grinding a cylinder prism, the plane tool is used, and 
the prism power only has to be considered. For example, a + 50 
axis 45 = I in would be marked and blocked as usual, and the 
apex ground to the proper thickness, say 2 mm. The base should 
then be 2 4/5 mm. thickness. The plane tool should be kept as 
accurate as possible for the reason that the slightest spherical 
power can readily be detected on the axis of a piano cylinder. 
This is ' also a difficult lens to polish, as will be explained. It 
should be remembered that a piano lens is the most difficult to 
grind. 

In grinding the wafers, it is only necessary to grind them 
small enough to be thin. The spherical lens is blocked, putting 
the surface that is correct down on the block, of course, and 
grind it down to about 30 mm. diameter. For horseshoe-shaped 
wafers they can be ground smaller, but if less than 25 mm. they 
will be too thin to handle. 

Tories are ground the same as a regular compound, obtain¬ 
ing the rough toric cylinders from the jobbers. If the com¬ 
bination to be ground is -f- i = 50, a -{- 50 toric rough cylinder 
is selected, and this will have the cylinder on the outside. This 
is blocked with the surface down, and — 5 ground on the inside. 
It should be remembered that these should be blocked on concave 
blocks so that the surface will fit. 

If any amount of roughing is to be done, do it on the extra 
tool kept for this purpose. This should be about 6 D. curve, and 
it is not necessary to keep it accurate. The idea is simply to have 
a tool with strong power to save the regular tools. Rough emery 
grinds the tool very quickly, and, consequently, throws it out 
of true. Quite a little time must then be spent to keep them 
in shape. 


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CHAPTER IX 


Surface Grinding—Continued 

TORIC AND SPECIAL LENSES 

Toric lenses are ground in the same way as compounds; that 
is, the spherical side. The rough toric cylinders are obtained 
from the jobbers in the moulded form, and this reduces the 
labor considerably. When it was necessary to grind them from 
the flat form a great deal of roughing had to be done. The 
blocking has already been described, and, if this is properly done, 
there is very little danger of breaking. In grinding torics it is 
very difficult to get the spherical power accurate for the reason 
that in grinding strong curves a little variation can hardly be 
detected, but when the curve is ground on the opposite side 
the total power of the lens is so weak as compared to the surfaces 
ground, that it is a very easy matter to grind the power .12 D. 
weaker or stronger. For this reason torics should be ordered 
of reliable houses that give this matter proper attention. One 
should also be particular to notice whether B. & L. or A. O. Co. 
rough toric cylinders are used. If an A. O. Co. piano-cylinder 
is to be ground on a B. & L. tool it should be 6.18 to be exact. 
(6.12 will be near enough.) If a B. & L. piano-cylinder is to 
be ground on an A. O. Co. tool, it should be 5.82 (5.87 will 
answer). 

If a -j- I = + 50 is to be ground, a -j- 50 toric cylinder 
with -f- 6 D. base curve is selected, and — 5 D. spherical ground 
on the inside. For -]- 2 = fl- 50, a — 4 D. spherical would be 
ground on the inside, and so on. As the spherical power in¬ 
creases, the inside curve decreases, so that if the full toric effect 
is desired it will be necessary to transpose the combination and 
grind it on a concave cylinder. 

If a — I = — 50 is to be ground, a — 50 cylinder with 
— 6 D. curve is selected, and -j- 5 sph. ground on the outside. 
Remember that the base is always 6 D., and, to produce the re¬ 
quired spherical, simply deduct the power desired, and this will be 
the curve to grind. Also do not forget that when grinding a -f 
and -f- combination on a — cylinder that the combination must 


79 



8 o 


The Making of a Mechanical Optician 


be transposed. This is the cause of many mistakes. For example: 
-[- I = + 50 if ground on a -|- cylinder will have a — 5 inside 
curve, or i D. weaker than the base. When transposed it will 
be + 1.50 = — 50, and the outside curve will be -f- 7.50, or 
1.50 D. stronger than the base. When 9 D. base curve is re¬ 
quired plus cylinders can most always be used, and it is rarely 



Fig. 59 


necessary to use minus. The curves are not only extreme, but 
the rough concave cylinders are expensive. 

Toric cylinders are usually ground on automatic machines, 
although a hand attachment for the regular surface machines 
can be obtained (Fig. 59). This work at present is not attempted 
by opticians, except in large shops or in localities where it re¬ 
quires some time to obtain the rough stock. As the sale of 
fused bifocals increase, however, more opticians will be obliged 
to grind cylinder or toric surfaces if they give prompt service to 
their customers. The hand attachment requires special blocks, 
having an iron rod running through the center (Fig. 60), to 
keep the axis of the lens in line with the tool. If the cylinder 
is fairly strong it will save time and also the wear on the tools 
to rough a spherical power on the glass first. It is then placed 
on the cylinder tool and the cylinder power put on with 3-F 
carborundum. This material cuts faster than emery and leaves 
a smooth surface. The machine can be run at almost any speed, 
but for the beginners it is better to use about 600 revolutions 


The Making of a Mechanical Optician 8i 

per minute. It is operated by the hand lever, the same as when 
grinding a spherical, but it is necessary to stop the machine to 
feed it. Care must also be used to keep the lens on the tool, as 
a slip is apt to not only spoil the lens, but the arms of the 
machine can also be broken very easily. After the carborundum. 
No. 4-F emery can be used and then the washed emery. The 
operations are the same as when grinding sphericals, except that 
it requires a great deal more time. For those that can afford 
it, the automatic machines are to be preferred, but they usually 
require much more time. There is a new machine just placed 
on the market, however, that will grind a pair of lenses quicker 
than a pair of sphericals can be ground by hand (Fig. 61). This 
will be of great benefit to the trade generally, as time is the most 
important part of the business to-day, except, of course, accuracy. 

Another machine that is used quite extensively is the “Her¬ 
cules” (Fig. 62). This machine does not require a separate 
spindle, but fits the spindle of any hand surface grinder. It does 
not revolve, but the spindle simply drives the lens-moving 
mechanism. 

Prescription houses are frequently asked if certain com¬ 
binations, especially prisms, can be made in torics. All combina¬ 
tions of lenses can be ground in toric form, but sometimes no 



better results are obtained. For example, — 12 = — i would 
be an extreme curve if ground in toric form, as the inside curve 
would be — 19 D. It would be much better to make it in double 
concave form with — 6 spherical on one side and — 6 = — 7 
on the other. If this form was not desired, it would be better 
to make it in the regular compound form. 









82 The Making of a Mechanical Optician 

It is also a common idea that strong concave combinations 
are thinner when ground in toric form. This is entirely wrong, 
and the only way to grind these is to make them lenticular. A 
lenticular lens is one having the power in the center only, usually 
in a circle, having a diameter of 22 mm. This is the stock form, 
but they can be ground with the circle as large as the width of 
the lens. The larger the circle, the thicker the lens, 
however. Outside the circle is usually piano, but when a large 
circle is desired, the outside can be ground convex. This 
reduces the thickness on the edge, so that it may be as thin as 
desired. This style of lens can also be made with an oval center, 
but these are quite difficult, and it is best to order them from the 
prescription houses. Lenticular lenses are very desirable and 
should be used more, and the reason that they are not is that 
opticians are not generally familiar with the different forms, or 
else they believe that the field is limited. 

In grinding lenses this style the first operation is to grind 
the power in the center, the same as any regular lens. This 
may be ground way out to the edge if desired. It is perhaps, 
just as well to do this when the power is not strong, but in the 
higher power lenses it requires too thick stock and it also makes 
unnecessary work. After the focus is ground and polished the 
center should be filled with sealing wax and then the piano tool 
and grind off until the circle is the correct size. This should not 
be over 25 mm., unless the focus is not over 10 D. If higher 
than this, it makes a better lens to grind it convex. The power 
of the outside curve will depend on the size of the circle desired, 
also the focus of the lens. The curve required will vary from 
6 D. upward, and, until you are experienced, it is a good plan 
to select a low power and try it. If the curve is not steep 
enough, try a stronger one. The outside surface should be 
polished befor.e the wax is removed. In referring to the outside 
curve of this style lens we mean the curve outside the circle 
and not on the opposite side of the lens. 

Fused bifocals are very interesting to grind, and as the 
blanks can now be obtained, the most difficult part has already 
been done. In ordering the blanks, it is necessary to give the 
full prescription, so that the proper blank can be selected. It 
must be remembered that the curve ground on the disk side 
will change the addition, so this must be taken into account. 


The Making of a Mechanical Optician 83 

It is also impossible to grind a cylinder on the disk side for this 
reason so in compounds an allowance for the spherical must be 
made. In making the blanks, a depression is ground in the base 
lens of a certain power, the curve having been calculated for 
the index of the flint to be used for the disk. For example: If 
a 10 D. will produce 2.50 D. addition, each diopter will add 
+ .25. If the blank was intended for a piano surface and a + i 
was ground on it, it would increase the reading addition .25 D. 
By this it will be seen that if the prescription called for distance 



mg. 61 


-f- I = — 50 axis 90, reading + 3 * 5 o> and the blank used was 
intended for a piano surface, the lens when finished would have 
for reading + 3.75. The blanks are blocked the same as any 
lens, but care must be used in heating. 

If the lens was not properly annealed it is very liable to 
break. The disk side is always ground first, as this must be 
brought down to the proper size. This is the most particular 
part of the work, as it can be easily ground too small. After 
the flint is ground off so that the surface is even it should be fined 




84 


The Making of a Mechanical Optician 


down very slowly, as this glass is very soft and grinds away 
quickly. In grinding a pair, always grind both disk surfaces 
first, so that the disks can be made the same size. Frequently, 
one lens will be ground so that the disk is the correct size, and 
then the other will have a scratch or imperfection in it, so that 
it must be ground smaller. It will then be necessary to reduce 
the other to match. In this way, grinding first one and then the 
other, it is possible to get them to match. After the disk side is 
ground, the other side can be brought down so as to make the 
finished lenses the proper thickness. If a cylinder is to be ground 
on the other side, it will be necessary to mark the axis, as the 
disk must be in the proper position. If the lens is twisted to 
correct the axis after the lens is finished the disk will be out of. 
center. If the axis is found to be off, it must be blocked again 
and reground. 

When the lens is laid out for axis, always try the tool with 
lens measure and see if the axis is in the proper position. There 
is nothing difiicult in grinding these lenses, but grind slowly, 
taking off a little at a time. In polishing, remember that the flint 
is soft and is easily made wavy. 

When the lens is ground and the finish is as near perfect 
as possible, the lens is ready to polish. The tool should be 
cleaned; and the lens rinsed in water. Then take a piece of felt, 
either round or square, as you prefer, and stick it on the tool. 
The material used is called 'Tacky,” and this is made from 
powdered rosin, or pitch, the same as used for blocking, and 
cut with alcohol, so that it is in the form of a paste. This is first 
applied to the surface of the tool with a brush, while it is running. 
The machine is then stopped and the felt pressed down firmly. 
Then start the machine and with a knife trim off the corners 
near the edge of the tool. This is where the art of polishing 
a lens, weak or strong, comes in. A convex lens may be polished 
strong by cutting the cloth large, and weak, by cutting the cloth 
small. A concave will be just the opposite, the lens will be 
strong when polished on a small cloth and weak on a large cloth. 

The rouge should be placed in a cup and mixed with water, 
so that it will be in the form of a paste; then place aside of this 
another cup containing plain water. Now apply the rouge with 
a brush, so that the felt will be well saturated; then place the 


The Making of a Mechanical Optician 85 

lens on the spindle and start the machine. As the lens revolves, 
move the lever forward and back, the same as when grinding to 
break up the rings that would form if it were held in one position. 
Apply the rouge occasionally, but do not let it get too dry, so 
that it will cake on the cloth. If it has this appearance, apply a 
little water. A lens will polish faster with a fairly dry cloth, but 
it cannot be too dry, of course. After polishing for two or 
three minutes, take the lens off the spindle and examine the sur¬ 
face. For this purpose a gas flame will give better results, as it 
has more or less flare. Daylight will answer, but electric light 



Figr. 62 


is not very good. The lens should be held in the hand, a little 
below the level of the eyes, in such a position that a good reflection 
of the flame will be found on the surface of the glass. By tilting 
it gradually so that the reflection moves across the surface, it will 
show up any imperfections, such as pits or scratches. When the 
glass has but a slight polish, the emery marks will be seen and 
these must be polished out. 

After the first inspection, and the lens has been found free 
from large pits and scratches, replace it on the spindle and polish 
a few minutes longer and then inspect again. As soon as the 
emery marks have all disappeared the lens is polished. If for 
any reason a scratch appears, or a pit of any size is found, it is 







86 The Making of a Mechanical Optician 

best to finish it again with the washed emery, as this will not 
only save time, but a better lens will be produced. When a lens 
is polished too long, the power is apt to be off, so that the quicker 
it is polished the better. Remember, however, that it will take 
just about so much time to polish a lens, and that just putting 
a glaze on the surface is not a polish. Beginners are very liable 
to make this mistake, and it requires quite a little practice to judge 
the surface of a lens. The cloth can be used several times, and, 
in fact, until it wears down too thin. When polishing a piano 
surface, such as a cylinder prism, never use a new cloth, but al¬ 
ways use one that has been used before. The nap on a new one 
will sometimes produce aberration. 

To remove a lens from the block, place it under a running 
faucet for several minutes. If the pitch is then started a little 
with a knife, the glass will come off easily. The lens should 
then be placed in a basin of turpentine to eat off the pitch. 


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CHAPTER X 


Soldering and Repairing—The Equipment 

Soldering is a part of mechanical optics not attempted by 
many opticians. While it is not very profitable, perhaps, it must be 
done occasionally to satisfy a customer. It also frequently hap¬ 
pens that it must be done in a hurry, as there is no time to send 
it away. There are many jobs that opticians are called upon to 
do in the way of small repairs and one thing that is necessary 
is to have proper equipment and the work then will not be difficult. 

Gas is very essential to do good soldering, although it can 
be done with an alcohol lamp. Alcohol is very unsatisfactory, 
for the reason that it is impossible to obtain a large flame and, 
therefore, there is not heat enough. 

There are several ways of arranging the gas, and possibly 
the simplest is to use an ordinary swinging gas bracket and re¬ 
move the lava tip. The size of the flame can then be regulated 
and an ordinary blowpipe used (Fig. 63). There are two styles. 



Fig. 63 — Blowpipe 


one having a bulb, forming a sort of reservoir for air. Either 
will do, however. There are also a number of different styles 
of blowpipes that are used principally by dentists. Some styles 
are quite elaborate, having valves to regulate the air and also the 
gas. These are not necessary, however, as one can be made 
very easily that would be simpler and better. It consists of a 
brass pipe with a rubber tube, which is attached to the gas at any 
convenient place, and another tube is inserted at an angle of 45°. 
On this is another rubber tube, which is held in the mouth. An 
ordinary pipe mouthpiece can be used if desired to hold in the 
mouth. The drawing (Fig. 64) gives a good idea of the con¬ 
struction. A blowpipe of this kind can be held in the hand 
in any position and is, therefore, much more convenient. 


81> 



go 


The Making of a Mechanical Optician 


There are many styles of soldering blocks, such as charcoal, 
asbestos and numberless patented ones. Webster s soldering block 
(Fig. 65) is the best and this, with a charcoal block, is all that 
is necessary. A borax slate (Fig. 66) will be needed and this 



is a slate having a concavity in which borax and water is mixed. 
The borax is prepared in tinfoil and can be used in the wrapper, 
so that it does not soil the fingers. In using put a few drops of 
water on the slate and rub the borax around a few times until 
the water looks milky. It is then applied with a small earners hair 
brush. Two jars will be required, one containing a solution of 



Fig:. 65—Webster’s soldering block 


one part sulphuric acid and two parts water. After the metal 
is heated in soldering it is blackened and if dipped in the acid, 
while hot, this is removed. It is then rinsed in plain water. 

These few articles are all that is required for the soldering, 
with the exception of solder. This can be obtained in several 










91 


The Making of a Mechanical Optician 

forms. The most common is silver, or hard solder. It is sold in 
flat strips, which can be cut with scissors into small bits, or it 
can be had all cut as small as desired. 

Although silver solder will answer all purposes a great many 
use gold solder. This can be obtained in all karats and is usually 



Fig. 66 — Borax slate 


claimed to be ‘‘easy flowing.” A spool of soft solder is handy to 
have around, but it should never be used in repairing spectacles. 

For tools one will need all the ordinary pliers, such as flat, 
round and snipe-nose; also the hollow-chop and cutting pliers. It 



Fig. 67—Spectacle and eyeglass stake 

will also be necessary to have two or three pairs of tweezers; one 
should be a good pair for picking up screws, etc., but the others 
can be cheap ones. The latter should have a slide so that they 
can be used to hold articles while soldering. As it is necessary 
to blow the flame on the points, it draws the temper so that they 
are of no use for any other purpose. A pin vise should be added 
for holding wire, etc. This is especially handy when filing down 
wire for rivets and things of that kind. A small vise should be 









92 


The Making of a Mechanical Optician 


screwed to the bench and a small anvil that stands on the bench 
will be found very convenient. A good assortment of screw¬ 
drivers should be selected; a good, substantial one with a wood 
handle and two or three others with different size blades and with 
swivel tops. A spectacle and eyeglass stake (Fig. 67) is very 
good to hold the endpieces of frames when extracting old screws. 
This is made with a wood base to stand on the bench, or it can 
be had for a vise. There are also a number of screw extractors 
on the market, but one of the spring punches fitted with a screw 
extractor is all right (Fig. 68). A couple of small hammers will 
be needed, and have one with a brass head. This will not mar 
or dent some of the softer metals as easily as steel. 

A good assortment of files is required—rat tail in one or 



Fig. 68 


two sizes; a flat one four or five inches long and five-eighths 
of an inch wide; a three and a half or four-inch half round; a 
square file, not too large; also a screw head file. For the cut, 
do not have them too coarse. If you have a good assortment 
have them range from Nos. 2 to 6; No. 4, however, is about the 
medium cut. It is well to have all these fitted with handles, as 
better work can be done. These can be obtained in assorted 
sizes for about five cents each. A burnisher is a good tool to 
have, but not too large a one. 

Buff sticks will be needed; also crocus and emery sticks. 
For buffing the ordinary felt stick is all right, but for smoothing 
and finishing for the buffing a leather stick is required. These 
can be bought with a kind of rawhide, quite thick; the stick 
is also very long. This should be cut down so that it is fairly 
thin; i. e., both the stick and the leather. This will give it a 


93 


The Making of a Mechanical Optician 

little spring and also allow it to be used in small places, such as 
under the shank of the bridge. The material used with this is 
Tripoli; or pulverized pumice, mixed with oil, will answer. There 
is, however, on the market now a prepared form of Tripoli called 
'‘Cut Quick.” This is in more convenient form. 

These sticks are used mostly, however, if one has no power. 
With power, wheels can be obtained to do most of this work 



Fig. 69 


much easier. There are certain jobs, however, where these 
sticks will be found very convenient. A buff head should be 
large enough to be substantial, so that it will run true; also that 
the bearings will not wear quickly. If it is too light, the shaft 
will spring easily also. Another point is that, if the bearings are 
not good, it cannot be run at a very high speed without rattling. 



Fig. 70 


and this is, of course, very objectionable. It should be run at a 
speed of from two to three thousand and, for all kinds of work, 
with the exception of finishing the ends of screws in frameless 
work, it should run towards you. This is a point that some 
workmen do not understand. They have outfits with one buff 

































































































94 


The Making of a Mechanical Optician 

head and this is, of course, fitted to run toward you for buffing, 
etc. Now a screw finisher must run left-handed, or from you, 
because if it did not it would turn the screw out instead of round¬ 
ing it. On the other hand, if we run the spindle the other way, 
or from you, the screw finisher will be running the right way, 
but the taper will be threaded the wrong way, so that the wheels 
will turn off instead of tightening. 

It is also the same with the chuck and nut. These will loosen 
so that nothing will stay in them. The only way to overcome 
this is to have a separate head for the screw finisher. If one 
does not have power these heads can be run very successfully 



Fig. 71 


by foot power. The foot wheel is better than the treadle, as 
more power and speed can be obtained. There are outfits all 
complete, however, with a zinc-lined box and treadle all belted 
if desired. By purchasing an ordinary buff head and screwing 
to a bench, then placing the foot wheel beneath, is very satis¬ 
factory. 

For wheels, get a number of stiff brushes (Fig. 69), having 
one each of one, two, three and four rows. These are used for 
cutting, as well as cleaning. Then a felt buff wheel from three 
to four inches diameter (Fig. 70), a cotton wheel about three 
inches diameter and also a rag wheel six to eight inches diameter 
(Fig. 71). Rag wheels come thin, so three to four will be re- 


The Making of a Mechanical Optician 


95 


quired. These should be placed together, with cardboard washers 
on either side, about two inches diameter, in place on the buff 
next the chuck and screw the nut up tightly. With this kind of 
a wheel better results can be obtained in fine polishing, such as 
putting on the final finish on a frame. Care must be used in 
polishing on this wheel, however, as temples and such things 
catch very easily if not held right. (This work will be explained 
in the next article.) 

For other small articles we would suggest a hand or jeweler’s 
brush; a roll of binding wire— i. c., soft iron wire, very small, for 
holding parts together while soldering; a stick of polishing rouge 
—get the kind wrapped up in tin foils so that you need not get 
any more on the fingers than possible; a solder burr for burring 
out the eye wire after soldering; a temple burr for end pieces; 
a bottle of soldering fluid. 

The completeness of the outfit depends, however, on what 
extent you intend to go into repairing. Years ago it was neces¬ 
sary to be fitted to do anything, from a simple solder to making 
a frame complete, but to-day it is entirely different, the goods 
cost less, are made better and a greater assortment of bridges 
can be kept in stock. Consequently, when an old frame is 
brought in for repairs it is often cheaper to give them a new 
one, or a new part, rather than attempt to repair it. 



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CHAPTER XI 


Soldering and Repairing—Continued 

Now as to the first step in preparing the break to be soldered. 
We will take, for instance, a break in the eye wire. First take a 
fine file, a half-round is the best, as it is pointed and fairly thin. 
It should be very fine; No. 6 is the best. With this file lightly 
over both sides, or, in other words, the parts to be exposed to 
the flame. Then place it on the soldering block and secure it 
with the clamps, so the ends just come together. Now mix the 
borax in the slate, first putting a few drops of water in the bottom, 
and then rub the borax around a few times, until you have ob¬ 
tained a milky fluid. Then, with a camel’s hair brush place a little 
on the parts to be soldered and apply a small piece of solder on 
one side of the break and you are ready to apply the heat. Turn 
on the gas so the flame will be about two inches high. 

If you are using the ordinary gas bracket, the tip having 
been removed, swing it directly in front of you and hold the blow¬ 
pipe in the right hand. The soldering block hold in the left, 
at the side of the flame. Now place the blowpipe side of the 
flame close to the outlet and blow a small, steady blue flame 
at the break (Fig. 72). This flame should be like a needle 
point, holding the work so the point that touches the frame will 
be about ^ inch in thickness. Heat the part on which the solder 
is placed, and as soon as the solder begins to flow throw the 
heat on the opposite side of the break, thus drawing the solder 
with the heat. 

If the work is held in the hands, the borax is placed on 
both sides and the solder on one side, as before. Apply the heat 
to the side on which the solder is placed, separating the parts 
until the solder is ready to flow. As soon as the solder starts 
to flow, dip both end of the break in the borax and apply the heat 
on the opposite side, as stated above. 

The cause of melting is blowing too much heat, either with 
too large a flame or blowing too long. Remember that it 
requires but a very small point of flame and little heat, but 


97 


^8 The Making of a Mechanical Optician 

properly placed. If a blowpipe is used as described in the pie- 
ceding article, it will be found much more convenient, as it can 
be held in any position. The soldering block can be held in 
the left hand, or laid on the bench, and the blowpipe in the right 
and the flame directed as desired. As soon as the solder flows 
and the eye wire seems to be connected, blow the flame all over 
the eye wire adjacent to the break for a second, to warm it, and 
then plunge it into the acid, and rinse in plain water. This 
will remove all the black and leave the frame in good condition. 

If for any reason the parts did not unite, it will be necessary 
to start all over from the beginning. Do not attempt to add more 



solder and keep blowing at it, for this may cause the frame to 
melt. File the parts again, put on more borax and start again. 

After the eye wire is soldered satisfactorily it will be neces¬ 
sary to file the break a little to smooth it, using, of course, the 
fine, or No. 6, cut. Then take the leather stick, referred to in the 
preceding article, and with tripoli, pumice and oil or Cut Quick, 
which is the prepared cutting material, go over the parts until 
all traces of file marks are removed. If power is used, the brush 
is the proper wheel and the cutting material is rubbed on by 
holding the stick against the wheel. Then with a solder burr, 
especially constructed for eye wire, burr out the inside of the 










The Making of a Mechanical Optician 99 

eye wire. This little tool is used in the buff head and run at a 
fairly high speed, say about 2000 revolutions per minute. 

You are now ready to polish. For this work use the cotton 
buff and this, of course, runs toward you. Rub plenty of the 
stick rouge into it while it is running. Now hold the frame 
tightly in both hands, with the eyes perpendicular, and the eye 
that has been soldered downward. In this manner there is no 
way for the frame to catch, provided you keep your mind on it. 
You will soon learn to protect the parts that are liable to catch 
with the hands, such as the end pieces and bridge. In all repair¬ 
ing it is best to remove the temples, as they are very liable to get 
in the way of the flame or catch in the wheel when buffing. 
After the frame is polished in good shape it should be washed 
with hot water and soap to remove all the dirt and rouge that 
collects in the joints. When replacing the lens it will be necessary 
to reduce it a little, as the eye is always made a little smaller 
when soldered. 

Most all solder jobs can be done without a soldering block 
if one is experienced, but quite a little practice is required. In 
this way the parts are held together with soft iron wire, called 
binding wire. 

Bridges can be obtained all ready to solder to the frame; 
that is, they are bent and grooved for the eye wire. The most 
common method to-day, however, is to use what is called unbent 
bridges. These consist of the bridge stock in assorted lengths, 
tapered about one the right size and thickness for the shank. In 
using this stock the principal feature lies in judging the length 
required. The medium sizes require 2^ to 2^ inches. First 
bend the crest or arch; this can be done over the handle of a tool 
or any round piece of wood. It is better to do it in this way 
than to attempt it with the hollow chop or periscopic pliers, as 
these dent the stock and must be taken out afterward. In gold 
filled this is impossible, as the gold will be finished too thin. 
After the arch is formed, bend up the shanks. These may 
possibly be too long and should be cut off, allowing stock enough, 
of course, for ffhe feet. A frameless bridge can be soldered 
on straight, and if preferred the frame can be made this way 
also. This style, when made at the factory, however, has a de¬ 
pression pressed in the eye wire to make a blind joint. In repair 
work this is not attempted. 


100 The Making of a Mechanical Optician 

The bending of the feet can best be done in a vise, as the 
stock must be turned edgewise, this being quite difficult. After 
the feet are bent they should be grooved with a float file; that is, 
one with rounded edges, just the right size for the eye wire. 
You are now ready to solder it to the frame. First prepare the 
eye wire by filing it lightly, the same as for any solder. It can 
then be placed on the soldering block, clamped in and the solder 
placed on the top of the foot of the bridge (Fig. 73). This 
operation can be done better in the hand, however. The eye 
wire can be held by the joint in the left hand, and the bridge 
in a pair of tweezers in the right hand. By having a slide on the 
tweezers, as before described, it is much easier. If the blowpipe 
is arranged so that it can stand on the bench, both hands will be 
free to work with. 

Another method is to use binding wire to hold the parts in 
position. In soldering the procedure is the same as before, plac¬ 
ing the borax and solder on the parts and heating them and as 
soon as the solder begins to flow, throw the heat in the direction 
you wish the solder to flow. Just enough solder must be used so 
that it will flow freely in the groove in the bridge, but it is un¬ 
necessary to have so much that it will flow outside all over the 
joint. Care must also be used to see that the bridge is in the 
center of the eye wire. When one eye is soldered, the other can 
be put on the same way. The frame can then be lined up and 
the bridge bent to dimensions. 

At this point it is well to see that the crest is the desired 
angle. If not, it can be formed with a pair of crest-angling 
pliers. If one does not have this tool the angle must be made 
first, while the stock is straight. For all saddle bridges, except 
the lowest ones, such as no height, the natural bend of the stock 
produces about 45°. “C” bridges, however, must be bent first. 

This operation is done by tilting the stock edgewise a little. This 
can be done by holding both ends of the stock securely with 
pliers and bending it over the edge of the bench pin. After the 
dimensions are made right any superfluous solder can be filed 
off with a fine file and finished with the buff stick and Cut Quick. 

With power this can be done much better and quicker. For 
this work use the brush wheel, putting on plenty of the cutting 
material. This wheel reaches in under the shank and smoothes 


The Making of a Mechanical Optician loi 

up the foot very nicely. After smoothing up in good shape it 
can be polished in the regular way, being very careful, however, 
to hold the frame tightly, so that the shank will not catch in wheel. 

One of the most common breaks is in the shank, at the turn. 
Formerly this was considered an unsatisfactory job, as, in order 
to make it strong, quite a little solder must be left in the turn. 
This was objectionable and yet, if finished in good shape, it made 
a very weak joint, as considerable strain comes at this point. 
Now this is a very common job, however, but the practice 



generally is to leave plenty of solder; in fact, sometimes it is 
pretty well filled up. For this operation it is best to use binding 
wire, so as to bring the parts together in the right position. The 
parts’ must be prepared in the same manner as before prescribed 
and proceed in the same manner. 

First prepare the eye wire by filing, then groove out the end 
piece, unless possibly it has just pulled out. Most breaks of this 
kind, however, are next to the end piece, so that a part of the 
eye wire is in the joint. When doing a job of this kind, be sure 
and remove the temple and screw and separate the joints. Do 
not, under any circumstances, attempt to solder an end piece 
on the eye wire, having them screwed together, for if you do you 
will find both end pieces soldered together and it will be like one 
mass, and it can never be taken apart. For this operation the 













102 


The Making of a Mechanical Optician 

end piece can be bound to the eye wire with binding wiie, and in 
this case wind it around the eye wire several times, quite a little 
distance back from the joint, and insert the other end through 
the screw hole and place it on the end of the eye wire. Do not 
attempt to bind it so that the eye wire comes near the solder. A 
simple way to do this work is to hold the frame in one hand and 
hold the joint on an old file, by inserting it in the screw hole. Do 
not use much solder in this operation, as it requires but the 
smallest piece to hold it securely. After the joint is soldered it 
will be necessary to burr out the eye wire and possibly reduce 
the lens a trifle. 

This material is worked the same as gold, except that one 
must bear in mind that there is only a very thin coating of gold 
over the base metal. One stroke of the file will cut through it, 
consequently the work must be done in such a manner that no 
filing is necessary. The great feature in handling gold filled is 
to use the smallest amount of solder possible. In this way it 
flows only into the break or between the joints. At the factory 
this work is usually covered with a coating of boracic acid to 
prevent discoloring. This is a powder and by wetting the frame 
and placing it in the powder enough will stick to it. The polishing 
should be done as quickly as possible, as the metal will not stand 
too much. 

Temples are very unsatisfactory to repair and only in cases 
of emergency should it be attempted. They are made in gold 
by drawing, and in gold filled by swedging. This process gives 
them the temper and spring. As soon as heat is applied to them 
they are annealed, and consequently are very soft. The best 
way to repair them is to use a ferrule. These are small pieces 
of tubing just the right size to slip over the broken ends, and 
as the base metal is solder it is only necessary to apply the heat 
and a good joint is obtained. This method leaves a bunch on the 
temple, but it is fairly strong. 

Spring stock must have considerable temper and spring, con¬ 
sequently when heat is applied they are practically useless. When 
one is broken near the end, or screw hole, a new hole can be 
punched, and although it makes it somewhat shorter it is very 
satisfactory. This is the only way any kind of a spring can be 
repaired, but even this method hardly pays, as springs can be 
obtained at a very low price. 


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CHAPTER XII 


Soldering and Repairing—Continued 

Steel goods are fast disappearing, although the better class 
of trade still call for them occasionally, preferring to wear them 
instead of gold. It seldom, if ever, pays to repair them, unless 
possibly it is to solder on an end piece. Steel is handled in much 
the same manner as gold, except, of course, silver solder is always 
used. The parts to be soldered are first filed bright, so that all 
traces of rust or foreign substances are removed. The parts are 
then dipped in borax and the heat and solder applied as described 
in the preceding article. This metal must be heated to a greater 
temperature; in other words, red hot. It is then plunged in the 
acid and this removes the black and also restores the temper to 
a certain extent. In finishing, the surplus solder is filed away 
and smoothed. The frame then should be rubbed with fine emery 
cloth to leave the steel bright. If it is to be nickeled, no more 
finishing is required. If the finish is bronze or blue it must be 
refinished to match as near as possible the old finish. 

At the factory the process is simplified by using hot sand. 
This produces an even color of any shade desired. For small 
shops it is hardly practical to attempt this method, as it is so 
seldom used. The easiest way is to use an alcohol lamp (gas will 
not answer, as the regular flame will blacken the work and a 
Bunsen burner has too much pressure). When using the ordinary 
jewelers’ alcohol lamp the wick should be pressed down so that 
a very small flame is obtained. The frame is then held in the 
left hand and the lamp in the right. Take the work to a place 
where good daylight can be obtained, as artificial light will not 
answer and neither will poor daylight produce satisfactory 
results. Now apply the flame directly to the metal (Fig. 74) 
and then remove it quickly so that it is heated but a very little. 
Repeat the operation several times, being careful to heat the 
frame but a second at a time. The color will be observed after 
the flame is removed and it will be noticed that it changes con¬ 
siderably in a second or two. Bronze will appear first, then blue, 


105 



io6 The Making of a Mechanical Optician 

and, if you are not careful, you will burn it and bright spots will 
appear. As soon as each spot is the desired color move the flame 
along. This is one of the most diflicult jobs in repairing, and, to 
produce an even color, it requires considerable practice. If the 
color gets too deep refinish the frame with emery cloth and try 
again. 

We are frequently called upon to cut a frame to fit old 
lenses. In this work all four end pieces, if it is a spectacle, must 
be moved. This requires four solders, so it is easily seen why this 
work is expensive. If one end piece on each side is moved the 
frame will be out of shape. Take one end piece at a time, blow 
the heat on to remove it, then refinish it and set it back on the 



eye wire slightly. The end that overlaps can then be filed off 
square. There are lens washers now on the market which are 
used extensively for this purpose and these are very satisfactory 
(Fig. 75). If they are not at hand, tinfoils, or, better still, tea 
lead, can be inserted in the eye wire to fill the open space. If 
the lens is only a very little loose, the end pieces can be filed 
slightly, but this method reduces the thickness so that it weakens 
the joints considerably. It is always preferable to fit new lenses 
if possible and this can frequently be done without the customer’s 
knowledge. 

Screws for all standard frames can be obtained cheaply so 
that it is well to have a good supply on hand. If one has taps 
for these threads they can be used to replace odd makes by simply 
tapping new threads (Fig. 76). The great difficulty is in 
removing the old screw, however. For most jobs the screw 



The Making of a Mechanical Optician 107 

extractor, referred to in Chapter X, will suffice. This can be 
used for end-piece screws if the head is not too far gone. If 
the head has been turned off completely it will probably be 
necessary to drill it out. Small twist drills, such as can be 
purchased in any hardware store, are used for this purpose. 
After the screw is drilled out the hole must be tapped and the 
new screw inserted. If the ends protrude they should be filed 
off carefully and the end piece polished. Stud screws, or screws 
that project, can frequently be removed successfully by filing a 



Figr. 75 


slot in the head with a screw head file. By then placing the 
frame in a stake (Chapter X) or against a solid square surface 
(if a stud screw hold it with a pair of stud or round-nose pliers) 
and. by using a wooden handle screwdriver it can be turned 
gradually. 

Fingerpiece mountings are used so extensively at the present 
time that it is well to be prepared to fit these while the customer 
waits. The factories will possibly replace these without charge, 
but it seems absurd to require a customer to go without their 
glasses for from one to three days when these can be inserted 


Fig. 76 


in a few moments. These springs can be obtained from the 
jobbers in gold filled for seventy-five cents a dozen pair and in 
gold for a dollar and a half. They come in rights and lefts and 
with two, three and four coils. The best mountings have four 
coils, as this produces an easier pressure and less liable to break. 
They are placed on the screw with the top ends over the inside 
edge of the straps, the coil being wound from left to right on the 
right side and from right to left on the left side (Fig. 77). The 
lower end is turned under the guard. After both ends are bent 





io8 The Making of a Mechanical Optician 

so they are secure they can be cut off fairly close, as will be indi¬ 
cated by an inspection of the guard. 

It is frequently necessary to fit new zylonite to guards, al¬ 
though it hardly pays, except on gold. There are a great many 
styles where the zylonite is peculiar in shape, and at the factories 
these are punched out with dies. When one is called upon to 
furnish one of the irregular shape the best that can be done is 
to cut it with shears or a knife as near as possible. This material 
can be smoothed and shaped wth a file so that it is possible to do 
a very good job. Zylonite can be obtained in any form, such as 
plain sheets, plain strips or in pieces ready to be fitted. The cor¬ 
rugations are pressed in at the factories, so it can be obtained in 



Figr. 77—Illustration showing position of right and left coil springs in their 
relation to the mounting 

this form if preferred. It is well to have a small assortment, 
however, so that all sizes can be obtained. Small wire, or even 
common pins, are used to secure it to the guard, but rivets, made 
especially for this purpose, should be kept on hand. The guard is 
already punched and small holes should be made in the zylonite 
just large enough to force the pins through. These are driven 
through from the back and are then cut off quite close and with a 
light hammer riveted gently. If the holes are just the right size 
it requires but a few taps. If plain zylonite is used, it will be 
necessary to corrugate it with a screw head file, making the cuts 
as small and as regular as possible. Scraps of shell can also be 
used for this purpose. 

Corks have to be fitted quite frequently, although many times, 
if they are only soiled, they can be washed with soap and water. 
This is the method employed when guards are slightly soiled 
from lying in stock. If they are quite bad and not worn down 
they can be sandpapered to look as good as new. For this pur- 




The Making of a Mechanical Optician 


109 


pose No. 00 sandpaper is used, any grade coarser than that will 
rough them. Cork can be obtained in the rough, cut the right 
size, or it can be had all rounded and finished with groove, ready 



Fig. 78 


to fit into the guard. The difference in price is so slight that it 
is better to use the finished. The old cork should be removed 
and the edges of the guard lifted with a burnisher or a knife just 
enough so that the cork will slide into the guard easily. The 
edges can then be burnished down so that it will hold securely. 
The end can then be trimmed off and if the guard is then too 
thick it can be sandpapered down. Some styles, such as No. o 
Anchor (Fig. 78), have a round disk which must be riveted and 
for any of these styles the disks can be ordered, cut to shape. The 
regular styles of guards in nickel and gold filled are low-priced, 
so that it is often cheaper to fit new ones than the charge 
made to cover the cost. 

Dowels, or rivets, as they are more generally called, have 
to be fitted to spectacle end pieces. In gold filled they loosen 
and fall out easily. In gold they wear so that the temples are 
loose and must be replaced. The only satisfactory way to tighten 
old gold temples is to fit new dowels, but for quick repairs spec 
washers can be obtained. Two, three, or as many as are necessary, 
are placed on the dowel to fill up the space in the joint and the 
end piece screwed together. Dowels can be obtained in the 
different sizes ready for use. They are tapered and left long so 
that they will fit any joint. When fitting these, it is only necessary 
to drive out the old one and insert the new. Place the joint 
on an anvil or vise so that the small end of the dowel can be 
driven into a hole and with a light hammer tap it lightly a 
few times and then try the temple. If it is not fairly tight, 
drive it in a little farther. If it is still loose drive it out 
again and with a small broach ream out the hole a little: The 


no The Making of a Mcchamcal Optician 

dowel can then be inserted and driven in slightly. Do not 
have the temple fit too snug but see that it works fairly stiff. 
If it works too freely it may be too loose after the ends of 
the dowel are finished off and it will then be necessary to do 
the work all over again. When the dowel is in place the ends 
should be cut off closely and finished first with a fine file and then 
polished on the buff wheel. If the finished dowels are not 
available, steel wire can be used, a size a little larger than the hole 
should be selected and a piece about a half an inch long‘cut off. 
This should be placed in a pin vise and filed to a slight taper. 
It can be done on the bench pin, revolving it with the left hand 



Fig. 79 


and filing with the right. In gold filled the dowels are usually 
rounded on the ends and for this metal the finished dowels for the 
particular grade that you are using should be kept in stock. A 
regular dowel can be used, however, and the ends rounded with 
a screw finisher. As gold filled is a softer metal the temples are 
fitted more loosely and the joint brought together tightly. This 
may not seem practical, but it is the only way the dowels can be 
made to hold in the end pieces. If they are fitted the same as 
gold the temple will work them loose. In some grades of gold 
filled the flush dowel is used and the largest end is punched 
slightly with a very small punch (Fig. 79). This is supposed 
to spread the head slightly to hold it in place. 

There are a number of small jobs that one is called upon to 
do that are interesting if time is of no account, such as drawing 
out gold temples, or balling them. To ball a gold temple it is 
only necessary to file the end slightly, to clean it and then dip it 
in the borax and apply the heat. This is very convenient when it 
is necessary to ‘shorten temples. Gold filled cannot be done in this 
manner but requires a gold ball soldered on the end. This is a 
little more difficult and is not attempted unless necessary. 




The Making of a Mechanical Optician iii 

The fitting of lorgnette springs is now quite common and this 
is a job that requires quite a little ingenuity. The springs can be 
obtained quite reasonable and if one has the time and cared to 
experiment with them a little practice will enable them to do as 
good a job as can be done at the factory. When fitting the center 
springs to plated styles it is necessary to have them replated. 
Platers when doing this work often use acid, which destroys the 
spring, so they should be cautioned regarding this point. The 
older styles, such as heirlooms, are very difficult to repair and 
should not be attempted. 


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